Cygwin Utilities
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## Cygwin Utilities

Cygwin comes with a number of command-line utilities that are used to manage the UNIX emulation portion of the Cygwin environment. While many of these reflect their UNIX counterparts, each was written specifically for Cygwin. You may use the long or short option names interchangeably; for example, `--help` and `-h` function identically. All of the Cygwin command-line utilities support the `--help` and `--version` options.

### cygcheck

    Usage: cygcheck PROGRAM [ -v ] [ -h ]
           cygcheck -c [ PACKAGE ... ] [ -d ]
           cygcheck -s [ -r ] [ -v ] [ -h ]
           cygcheck -k
           cygcheck -f FILE [ FILE ... ]
           cygcheck -l [ PACKAGE ... ]
           cygcheck -p REGEXP
    List system information, check installed packages, or query package database.

    At least one command option or a PROGRAM is required, as shown above.

      PROGRAM              list library (DLL) dependencies of PROGRAM
      -c, --check-setup    show installed version of PACKAGE and verify integrity
                           (or for all installed packages if none specified)
      -d, --dump-only      just list packages, do not verify (with -c)
      -s, --sysinfo        produce diagnostic system information (implies -c -d)
      -r, --registry       also scan registry for Cygwin settings (with -s)
      -k, --keycheck       perform a keyboard check session (must be run from a
                           plain console only, not from a pty/rxvt/xterm)
      -f, --find-package   find the package that FILE belongs to
      -l, --list-package   list contents of PACKAGE (or all packages if none given)
      -p, --package-query  search for REGEXP in the entire cygwin.com package
                           repository (requies internet connectivity)
      -v, --verbose        produce more verbose output
      -h, --help           annotate output with explanatory comments when given
                           with another command, otherwise print this help
      -V, --version        print the version of cygcheck and exit

    Note: -c, -f, and -l only report on packages that are currently installed. To
      search all official Cygwin packages use -p instead.  The -p REGEXP matches
      package names, descriptions, and names of files/paths within all packages.

The cygcheck program is a diagnostic utility for dealing with Cygwin programs. If you are familiar with dpkg or rpm, cygcheck is similar in many ways. (The major difference is that setup.exe handles installing and uninstalling packages; see the section called “Internet Setup” for more information.)

The `-c` option checks the version and status of installed Cygwin packages. If you specify one or more package names, cygcheck will limit its output to those packages, or with no arguments it lists all packages. A package will be marked `Incomplete` if files originally installed are no longer present. The best thing to do in that situation is reinstall the package with setup.exe. To see which files are missing, use the `-v` option. If you do not need to know the status of each package and want cygcheck to run faster, add the `-d` option and cygcheck will only output the name and version for each package.

If you list one or more programs on the command line, cygcheck will diagnose the runtime environment of that program or programs, providing the names of DLL files on which the program depends. If you specify the `-s` option, cygcheck will give general system information. If you list one or more programs on the command line and specify `-s`, cygcheck will report on both.

The `-f` option helps you to track down which package a file came from, and `-l` lists all files in a package. For example, to find out about `/usr/bin/less` and its package:

Example 3.4. Example cygcheck usage

    $ cygcheck -f /usr/bin/less
    less-381-1

    $ cygcheck -l less
    /usr/bin/less.exe
    /usr/bin/lessecho.exe
    /usr/bin/lesskey.exe
    /usr/man/man1/less.1
    /usr/man/man1/lesskey.1

The `-h` option prints additional helpful messages in the report, at the beginning of each section. It also adds table column headings. While this is useful information, it also adds some to the size of the report, so if you want a compact report or if you know what everything is already, just leave this out.

The `-v` option causes the output to be more verbose. What this means is that additional information will be reported which is usually not interesting, such as the internal version numbers of DLLs, additional information about recursive DLL usage, and if a file in one directory in the PATH also occurs in other directories on the PATH.

The `-r` option causes cygcheck to search your registry for information that is relevent to Cygwin programs. These registry entries are the ones that have "Cygwin" in the name. If you are paranoid about privacy, you may remove information from this report, but please keep in mind that doing so makes it harder to diagnose your problems.

In contrast to the other options that search the packages that are installed on your local system, the `-p` option can be used to search the entire official Cygwin package repository. It takes as argument a Perl-compatible regular expression which is used to match package names, package descriptions, and path/filenames of the contents of packages. This feature requires an active internet connection, since it must query the `cygwin.com` web site. In fact, it is equalivant to the search that is available on the Cygwin package listing page.

For example, perhaps you are getting an error because you are missing a certain DLL and you want to know which package includes that file:

Example 3.5. Searching all packages for a file

    $ cygcheck -p 'cygintl-2\.dll'
    Found 1 matches for 'cygintl-2\.dll'.

    libintl2-0.12.1-3         GNU Internationalization runtime library

    $ cygcheck -p 'libexpat.*\.a'
    Found 2 matches for 'libexpat.*\.a'.

    expat-1.95.7-1            XML parser library written in C
    expat-1.95.8-1            XML parser library written in C

    $ cygcheck -p '/ls\.exe'
    Found 2 matches for '/ls\.exe'.

    coreutils-5.2.1-5         GNU core utilities (includes fileutils, sh-utils and textutils)
    coreutils-5.3.0-6         GNU core utilities (includes fileutils, sh-utils and textutils)

Note that this option takes a regular expression, not a glob or wildcard. This means that you need to use `.*` if you want something similar to the wildcard `*` commonly used in filename globbing. Similarly, to match the period character you should use `\.` since the `.` character in a regexp is a metacharacter that will match any character. Also be aware that the characters such as `\` and `*` are shell metacharacters, so they must be either escaped or quoted, as in the example above.

The third example above illustrates that if you want to match a whole filename, you should include the `/` path seperator. In the given example this ensures that filenames that happen to end in `ls.exe` such as `ncftpls.exe` are not shown. Note that this use does not mean "look for packages with `ls` in the root directory," since the `/` can match anywhere in the path. It's just there to anchor the match so that it matches a full filename.

By default the matching is case-sensitive. To get a case insensitive match, begin your regexp with `(?i)` which is a PCRE-specific feature. For complete documentation on Perl-compatible regular expression syntax and options, read the perlre manpage, or one of many websites such as `perldoc.com` that document the Perl language.

The cygcheck program should be used to send information about your system for troubleshooting when requested. When asked to run this command save the output so that you can email it, for example:

    C:\cygwin> cygcheck -s -v -r -h > cygcheck_output.txt

### cygpath

    Usage: cygpath (-d|-m|-u|-w|-t TYPE) [-f FILE] [OPTION]... NAME...
           cygpath [-c HANDLE]
           cygpath [-ADHOPSW]
           cygpath [-F ID]
    Convert Unix and Windows format paths, or output system path information

    Output type options:
      -d, --dos             print DOS (short) form of NAMEs (C:\PROGRA~1\)
      -m, --mixed           like --windows, but with regular slashes (C:/WINNT)
      -M, --mode            report on mode of file (currently binmode or textmode)
      -u, --unix            (default) print Unix form of NAMEs (/cygdrive/c/winnt)
      -w, --windows         print Windows form of NAMEs (C:\WINNT)
      -t, --type TYPE       print TYPE form: 'dos', 'mixed', 'unix', or 'windows'
    Path conversion options:
      -a, --absolute        output absolute path
      -l, --long-name       print Windows long form of NAMEs (with -w, -m only)
      -p, --path            NAME is a PATH list (i.e., '/bin:/usr/bin')
      -s, --short-name      print DOS (short) form of NAMEs (with -w, -m only)
    System information:
      -A, --allusers        use `All Users' instead of current user for -D, -P
      -D, --desktop         output `Desktop' directory and exit
      -H, --homeroot        output `Profiles' directory (home root) and exit
      -O, --mydocs          output `My Documents' directory and exit
      -P, --smprograms      output Start Menu `Programs' directory and exit
      -S, --sysdir          output system directory and exit
      -W, --windir          output `Windows' directory and exit
      -F, --folder ID       output special folder with numeric ID and exit
    Other options:
      -f, --file FILE       read FILE for input; use - to read from STDIN
      -o, --option          read options from FILE as well (for use with --file)
      -c, --close HANDLE    close HANDLE (for use in captured process)
      -i, --ignore          ignore missing argument
      -h, --help            output usage information and exit
      -v, --version         output version information and exit

The cygpath program is a utility that converts Windows native filenames to Cygwin POSIX-style pathnames and vice versa. It can be used when a Cygwin program needs to pass a file name to a native Windows program, or expects to get a file name from a native Windows program. Alternatively, cygpath can output information about the location of important system directories in either format.

The `-u` and `-w` options indicate whether you want a conversion to UNIX (POSIX) format (`-u`) or to Windows format (`-w`). Use the `-d` to get DOS-style (8.3) file and path names. The `-m` option will output Windows-style format but with forward slashes instead of backslashes. This option is especially useful in shell scripts, which use backslashes as an escape character.

In combination with the `-w` option, you can use the `-l` and `-s` options to use normal (long) or DOS-style (short) form. The `-d` option is identical to `-w` and `-s` together.

The `-p` option means that you want to convert a path-style string rather than a single filename. For example, the PATH environment variable is semicolon-delimited in Windows, but colon-delimited in UNIX. By giving `-p` you are instructing cygpath to convert between these formats.

The `-i` option supresses the print out of the usage message if no filename argument was given. It can be used in make file rules converting variables that may be omitted to a proper format. Note that cygpath output may contain spaces (C:\Program Files) so should be enclosed in quotes.

Example 3.6. Example cygpath usage

    #!/bin/sh
    if [ "${1}" = "" ];
    	then
    		XPATH=".";
    	else
    		XPATH="$(cygpath -w "${1}")";
    fi
    explorer $XPATH &

The capital options `-D`, `-H`, `-P`, `-S`, and `-W` output directories used by Windows that are not the same on all systems, for example `-S` might output C:\WINNT\system32 or C:\Windows\System32. The `-H` shows the Windows profiles directory that can be used as root of home. The `-A` option forces use of the "All Users" directories instead of the current user for the `-D`, `-O` and `-P` options. The `-F` outputs other special folders specified by their internal numeric code (decimal or 0xhex). For valid codes and symbolic names, see the CSIDL_* definitions in the include file /usr/include/w32api/shlobj.h from package w32api. The current valid range of codes for folders is 0 (Desktop) to 59 (CDBurn area). By default the output is in UNIX (POSIX) format; use the `-w` or `-d` options to get other formats.

### dumper

    Usage: dumper [OPTION] FILENAME WIN32PID
    Dump core from WIN32PID to FILENAME.core

    -d, --verbose  be verbose while dumping
    -h, --help     output help information and exit
    -q, --quiet    be quiet while dumping (default)
    -v, --version  output version information and exit

The dumper utility can be used to create a core dump of running Windows process. This core dump can be later loaded to gdb and analyzed. One common way to use dumper is to plug it into cygwin's Just-In-Time debugging facility by adding

    error_start=x:\path\to\dumper.exe

to the CYGWIN environment variable. Please note that `x:\path\to\dumper.exe` is Windows-style and not cygwin path. If `error_start` is set this way, then dumper will be started whenever some program encounters a fatal error.

dumper can be also be started from the command line to create a core dump of any running process. Unfortunately, because of a Windows API limitation, when a core dump is created and dumper exits, the target process is terminated too.

To save space in the core dump, dumper doesn't write those portions of target process' memory space that are loaded from executable and dll files and are unchangeable, such as program code and debug info. Instead, dumper saves paths to files which contain that data. When a core dump is loaded into gdb, it uses these paths to load appropriate files. That means that if you create a core dump on one machine and try to debug it on another, you'll need to place identical copies of the executable and dlls in the same directories as on the machine where the core dump was created.

### getfacl

    Usage: getfacl [-adn] FILE [FILE2...]
    Display file and directory access control lists (ACLs).

      -a, --all      display the filename, the owner, the group, and
                     the ACL of the file
      -d, --dir      display the filename, the owner, the group, and
                     the default ACL of the directory, if it exists
      -h, --help     output usage information and exit
      -n, --noname   display user and group IDs instead of names
      -v, --version  output version information and exit

    When multiple files are specified on the command line, a blank
    line separates the ACLs for each file.

For each argument that is a regular file, special file or directory, getfacl displays the owner, the group, and the ACL. For directories getfacl displays additionally the default ACL. With no options specified, getfacl displays the filename, the owner, the group, and both the ACL and the default ACL, if it exists. For more information on Cygwin and Windows ACLs, see see the section called “Using Windows security in Cygwin” in the Cygwin User's Guide. The format for ACL output is as follows:

         # file: filename
         # owner: name or uid
         # group: name or uid
         user::perm
         user:name or uid:perm
         group::perm
         group:name or gid:perm
         mask:perm
         other:perm
         default:user::perm
         default:user:name or uid:perm
         default:group::perm
         default:group:name or gid:perm
         default:mask:perm
         default:other:perm

### kill

    Usage: kill [-f] [-signal] [-s signal] pid1 [pid2 ...]
           kill -l [signal]
    Send signals to processes

     -f, --force     force, using win32 interface if necessary
     -l, --list      print a list of signal names
     -s, --signal    send signal (use kill --list for a list)
     -h, --help      output usage information and exit
     -v, --version   output version information and exit

The kill program allows you to send arbitrary signals to other Cygwin programs. The usual purpose is to end a running program from some other window when ^C won't work, but you can also send program-specified signals such as SIGUSR1 to trigger actions within the program, like enabling debugging or re-opening log files. Each program defines the signals they understand.

You may need to specify the full path to use kill from within some shells, including bash, the default Cygwin shell. This is because bash defines a kill builtin function; see the bash man page under BUILTIN COMMANDS for more information. To make sure you are using the Cygwin version, try

    $ /bin/kill --version

which should give the Cygwin kill version number and copyright information.

Unless you specific the `-f` option, the "pid" values used by kill are the Cygwin pids, not the Windows pids. To get a list of running programs and their Cygwin pids, use the Cygwin ps program. ps -W will display all windows pids.

The kill -l option prints the name of the given signal, or a list of all signal names if no signal is given.

To send a specific signal, use the `-signN` option, either with a signal number or a signal name (minus the "SIG" part), like these examples:

Example 3.7. Using the kill command

    $ kill 123
    $ kill -1 123
    $ kill -HUP 123
    $ kill -f 123

Here is a list of available signals, their numbers, and some commentary on them, from the file `<sys/signal.h>`, which should be considered the official source of this information.

    SIGHUP       1    hangup
    SIGINT       2    interrupt
    SIGQUIT      3    quit
    SIGILL       4    illegal instruction (not reset when caught)
    SIGTRAP      5    trace trap (not reset when caught)
    SIGABRT      6    used by abort
    SIGEMT       7    EMT instruction
    SIGFPE       8    floating point exception
    SIGKILL      9    kill (cannot be caught or ignored)
    SIGBUS      10    bus error
    SIGSEGV     11    segmentation violation
    SIGSYS      12    bad argument to system call
    SIGPIPE     13    write on a pipe with no one to read it
    SIGALRM     14    alarm clock
    SIGTERM     15    software termination signal from kill
    SIGURG      16    urgent condition on IO channel
    SIGSTOP     17    sendable stop signal not from tty
    SIGTSTP     18    stop signal from tty
    SIGCONT     19    continue a stopped process
    SIGCHLD     20    to parent on child stop or exit
    SIGTTIN     21    to readers pgrp upon background tty read
    SIGTTOU     22    like TTIN for output if (tp->t_local&LTOSTOP)
    SIGPOLL     23    System V name for SIGIO
    SIGXCPU     24    exceeded CPU time limit
    SIGXFSZ     25    exceeded file size limit
    SIGVTALRM   26    virtual time alarm
    SIGPROF     27    profiling time alarm
    SIGWINCH    28    window changed
    SIGLOST     29    resource lost (eg, record-lock lost)
    SIGUSR1     30    user defined signal 1
    SIGUSR2     31    user defined signal 2

### mkgroup

    Usage: mkgroup [OPTION]...
    Print /etc/group file to stdout

    Options:
       -l,--local [machine[,offset]]
                               print local groups with gid offset offset
                               (from local machine if no machine specified)
       -L,--Local [machine[,offset]]
                               ditto, but generate groupname with machine prefix
       -d,--domain [domain[,offset]]
                               print domain groups with gid offset offset
                               (from current domain if no domain specified)
       -D,--Domain [domain[,offset]]
                               ditto, but generate groupname with machine prefix
       -c,--current            print current group
       -C,--Current            ditto, but generate groupname with machine or
                               domain prefix
       -S,--separator char     for -L, -D, -C use character char as domain\group
                               separator in groupname instead of the default '\'
       -o,--id-offset offset   change the default offset (10000) added to gids
                               in domain or foreign server accounts.
       -g,--group groupname    only return information for the specified group
                               one of -l, -L, -d, -D must be specified, too
       -b,--no-builtin         don't print BUILTIN groups
       -U,--unix grouplist     additionally print UNIX groups when using -l or -L
                               on a UNIX Samba server
                               grouplist is a comma-separated list of groupnames
                               or gid ranges (root,-25,50-100).
    			   (enumerating large ranges can take a long time!)
       -s,--no-sids            (ignored)
       -u,--users              (ignored)
       -h,--help               print this message
       -v,--version            print version information and exit

    Default is to print local groups on stand-alone machines, plus domain
    groups on domain controllers and domain member machines.

The mkgroup program can be used to help configure Cygwin by creating a `/etc/group` file. Its use is essential to include Windows security information.

The command is initially called by setup.exe to create a default `/etc/group`. This should be sufficient in most circumstances. However, especially when working in a multi-domain environment, you can use mkgroup manually to create a more complete `/etc/group` file for all domains. Especially when you have the same group name used on multiple machines or in multiple domains, you can use the `-D`, `-L` and `-C` options to create unique domain\group style groupnames.

Note that this information is static. If you change the group information in your system, you'll need to regenerate the group file for it to have the new information.

The `-d/-D` and `-l/-L` options allow you to specify where the information comes from, the local SAM of a machine or from the domain, or both. With the `-d/-D` options the program contacts a Domain Controller, which my be unreachable or have restricted access. Comma-separated from the machine or domain, you can specify an offset which is used as base added to the group's RID to compute the gid (offset + RID = gid). This allows to create the same gids every time you re-run mkgroup. For very simple needs, an entry for the current user's group can be created by using the option `-c` or `-C`. If you want to use one of the `-D`, `-L` or `-C` options, but you don't like the backslash as domain/group separator, you can specify another separator using the `-S` option, for instance

Example 3.8. Setting up group entry for current user with different domain/group separator

    $ mkgroup -C -S+ > /etc/group
    $ cat /etc/group
    DOMAIN+my_group:S-1-5-21-2913048732-1697188782-3448811101-1144:11144:

The `-o` option allows for special cases (such as multiple domains) where the GIDs might match otherwise. The `-g` option only prints the information for one group. The `-U` option allows to enumerate the standard UNIX groups on a Samba machine. It's used together with `-l samba-server` or `-L samba-server`. The normal UNIX groups are usually not enumerated, but they can show up as group in ls -l output.

### mkpasswd

    Usage: mkpasswd [OPTIONS]...
    Print /etc/passwd file to stdout

    Options:
       -l,--local [machine[,offset]]
                               print local user accounts with uid offset offset
                               (from local machine if no machine specified)
       -L,--Local [machine[,offset]]
                               ditto, but generate username with machine prefix
       -d,--domain [domain[,offset]]
                               print domain accounts with uid offset offset
                               (from current domain if no domain specified)
       -D,--Domain [domain[,offset]]
                               ditto, but generate username with domain prefix
       -c,--current            print current user
       -C,--Current            ditto, but generate username with machine or
                               domain prefix
       -S,--separator char     for -L, -D, -C use character char as domain\user
                               separator in username instead of the default '\'
       -o,--id-offset offset   change the default offset (10000) added to uids
                               in domain or foreign server accounts.
       -u,--username username  only return information for the specified user
                               one of -l, -L, -d, -D must be specified, too
       -p,--path-to-home path  use specified path instead of user account home dir
                               or /home prefix
       -m,--no-mount           don't use mount points for home dir
       -U,--unix userlist      additionally print UNIX users when using -l or -L\
                               on a UNIX Samba server
                               userlist is a comma-separated list of usernames
                               or uid ranges (root,-25,50-100).
                               (enumerating large ranges can take a long time!)
       -s,--no-sids            (ignored)
       -g,--local-groups       (ignored)
       -h,--help               displays this message
       -v,--version            version information and exit

    Default is to print local accounts on stand-alone machines, domain accounts
    on domain controllers and domain member machines.

The mkpasswd program can be used to help configure Cygwin by creating a `/etc/passwd` from your system information. Its use is essential to include Windows security information. However, the actual passwords are determined by Windows, not by the content of `/etc/passwd`.

The command is initially called by setup.exe to create a default `/etc/passwd`. This should be sufficient in most circumstances. However, especially when working in a multi-domain environment, you can use mkpasswd manually to create a more complete `/etc/passwd` file for all domains. Especially when you have the same user name used on multiple machines or in multiple domains, you can use the `-D`, `-L` and `-C` options to create unique domain\user style usernames.

Note that this information is static. If you change the user information in your system, you'll need to regenerate the passwd file for it to have the new information.

The `-d/-D` and `-l/-L` options allow you to specify where the information comes from, the local machine or the domain (default or given), or both. With the `-d/-D` options the program contacts the Domain Controller, which may be unreachable or have restricted access. Comma-separated from the machine or domain, you can specify an offset which is used as base added to the user's RID to compute the uid (offset + RID = uid). This allows to create the same uids every time you re-run mkpasswd. An entry for the current user can be created by using the option `-c` or `-C`. If you want to use one of the `-D`, `-L` or `-C` options, but you don't like the backslash as domain/group separator, you can specify another separator using the `-S` option, simialar to the mkgroup. The `-o` option allows for special cases (such as multiple domains) where the UIDs might match otherwise. The `-m` option bypasses the current mount table so that, for example, two users who have a Windows home directory of H: could mount them differently. For more information on SIDs, see the section called “Using Windows security in Cygwin” in the Cygwin User's Guide. The `-p` option causes mkpasswd to use the specified prefix instead of the account home dir or `/home/` . For example, this command:

Example 3.9. Using an alternate home root

    $ mkpasswd -l -p "$(cygpath -H)" > /etc/passwd

would put local users' home directories in the Windows 'Profiles' directory. The `-u` option creates just an entry for the specified user. The `-U` option allows to enumerate the standard UNIX users on a Samba machine. It's used together with `-l samba-server` or `-L samba-server`. The normal UNIX users are usually not enumerated, but they can show up as file owners in ls -l output.

### mount

    Usage: mount [OPTION] [<win32path> <posixpath>]
    Display information about mounted filesystems, or mount a filesystem

      -c, --change-cygdrive-prefix  change the cygdrive path prefix to <posixpath>
      -f, --force                   force mount, don't warn about missing mount
                                    point directories
      -h, --help                    output usage information and exit
      -m, --mount-entries           write fstab entries to replicate mount points
                                    and cygdrive prefixes
      -o, --options X[,X...]        specify mount options
      -p, --show-cygdrive-prefix    show user and/or system cygdrive path prefix
      -v, --version                 output version information and exit

The mount program is used to map your drives and shares onto Cygwin's simulated POSIX directory tree, much like as is done by mount commands on typical UNIX systems. However, in contrast to mount points given in `/etc/fstab`, mount points created or changed with mount are not persistent. They disappear immediately after the last process of the current user exited. Please see the section called “The Cygwin Mount Table” for more information on the concepts behind the Cygwin POSIX file system and strategies for using mounts. To remove mounts temporarily, use umount

#### Using mount

If you just type mount with no parameters, it will display the current mount table for you.

Example 3.10. Displaying the current set of mount points

    c:\cygwin\> mount
    c:\cygwin\bin on /usr/bin type ntfs (binary)
    c:\cygwin\lib on /usr/lib type ntfs (binary)
    c:\cygwin on / type ntfs (binary)
    c: on /c type ntfs (binary,user,noumount)
    d: on /d type fat (binary,user,noumount)

In this example, c:\cygwin is the POSIX root and D drive is mapped to `/d`. Note that in this case, the root mount is a system-wide mount point that is visible to all users running Cygwin programs, whereas the `/d` mount is only visible to the current user.

The mount utility is also the mechanism for adding new mounts to the mount table. The following example demonstrates how to mount the directory `//pollux/home/joe/data` to `/data` for the duration of the current session.

Example 3.11. Adding mount points

    c:\cygwin\> ls /data
    ls: /data: No such file or directory
    c:\cygwin\> mount //pollux/home/joe/data /data
    mount: warning - /data does not exist!
    c:\cygwin\> mount
    //pollux/home/joe/data on /data type smbfs (binary)
    c:/cygwin/bin on /usr/bin type ntfs (binary)
    c:/cygwin/lib on /usr/lib type ntfs (binary)
    c:/cygwin on / type ntfs (binary)
    c: on /c type ntfs (binary,user,noumount)
    d: on /d type fat (binary,user,noumount)

A given POSIX path may only exist once in the mount table. Attempts to replace the mount will fail with a busy error. The `-f` (force) option causes the old mount to be silently replaced with the new one, provided the old mount point was a user mount point. It's not valid to replace system-wide mount points. Additionally, the `-f` option will silence warnings about the non-existence of directories at the Win32 path location.

The `-o` option is the method via which various options about the mount point may be recorded. The following options are available (note that most of the options are duplicates of other mount flags):

      acl        - Use the filesystem's access control lists (ACLs) to
                   implement real POSIX permissions (default).
      noacl      - Ignore ACLs and fake POSIX permissions.
      binary     - Files default to binary mode (default).
      text       - Files default to CRLF text mode line endings.
      exec       - Treat all files below mount point as executable.
      notexec    - Treat all files below mount point as not executable.
      cygexec    - Treat all files below mount point as cygwin executables.
      nosuid     - No suid files are allowed (currently unimplemented)
      posix=0    - Switch off case sensitivity for paths under this mount point.
      posix=1    - Switch on case sensitivity for paths under this mount point
                   (default).

For a more complete description of the mount options and the `/etc/fstab` file, see the section called “The Cygwin Mount Table”.

Note that all mount points added with mount are user mount points. System mount points can only be specified in the `/etc/fstab` file.

The `-m` option causes the mount utility to output the current mount table in a series of fstab entries. This allows You can save this output as a backup when experimenting with the mount table. Copy the output to `/etc/fstab` to restore the old state. It also makes moving your settings to a different machine much easier.

#### Cygdrive mount points

Whenever Cygwin cannot use any of the existing mounts to convert from a particular Win32 path to a POSIX one, Cygwin will, instead, convert to a POSIX path using a default mount point: `/cygdrive`. For example, if Cygwin accesses `z:\foo` and the z drive is not currently in the mount table, then `z:\` will be accessible as `/cygdrive/z`. The mount utility can be used to change this default automount prefix through the use of the "--change-cygdrive-prefix" option. In the following example, we will set the automount prefix to `/`:

Example 3.12. Changing the default prefix

    c:\cygwin\> mount --change-cygdrive-prefix /

Note that the cygdrive prefix can be set both per-user and system-wide, and that as with all mounts, a user-specific mount takes precedence over the system-wide setting. The mount utility creates system-wide mounts by default if you do not specify a type. Use the `-s` or `-u` flag to indicate a system or user mount, respectively. You can always see the user and system cygdrive prefixes with the `-p` option. Using the `-b` flag with `--change-cygdrive-prefix` makes all new automounted filesystems default to binary mode file accesses.

#### Limitations

Limitations: there is a hard-coded limit of 30 mount points. Also, although you can mount to pathnames that do not start with "/", there is no way to make use of such mount points.

Normally the POSIX mount point in Cygwin is an existing empty directory, as in standard UNIX. If this is the case, or if there is a place-holder for the mount point (such as a file, a symbolic link pointing anywhere, or a non-empty directory), you will get the expected behavior. Files present in a mount point directory before the mount become invisible to Cygwin programs.

It is sometimes desirable to mount to a non-existent directory, for example to avoid cluttering the root directory with names such as `a`, `b`, `c` pointing to disks. Although mount will give you a warning, most everything will work properly when you refer to the mount point explicitly. Some strange effects can occur however. For example if your current working directory is `/dir`, say, and `/dir/mtpt` is a mount point, then `mtpt` will not show up in an ls or echo * command and find . will not find `mtpt`.

### passwd

    Usage: passwd [OPTION] [USER]
    Change USER's password or password attributes.

    User operations:
      -l, --lock               lock USER's account.
      -u, --unlock             unlock USER's account.
      -c, --cannot-change      USER can't change password.
      -C, --can-change         USER can change password.
      -e, --never-expires      USER's password never expires.
      -E, --expires            USER's password expires according to system's
                               password aging rule.
      -p, --pwd-not-required   no password required for USER.
      -P, --pwd-required       password is required for USER.
      -R, --reg-store-pwd      enter password to store it in the registry for
                               later usage by services to be able to switch
                               to this user context with network credentials."

    System operations:
      -i, --inactive NUM       set NUM of days before inactive accounts are disabled
                               (inactive accounts are those with expired passwords).
      -n, --minage DAYS        set system minimum password age to DAYS days.
      -x, --maxage DAYS        set system maximum password age to DAYS days.
      -L, --length LEN         set system minimum password length to LEN.

    Other options:
      -S, --status             display password status for USER (locked, expired,
                               etc.) plus global system password settings.
      -h, --help               output usage information and exit.
      -v, --version            output version information and exit.

    If no option is given, change USER's password.  If no user name is given,
    operate on current user.  System operations must not be mixed with user
    operations.  Don't specify a USER when triggering a system operation.

    Don't specify a user or any other option together with the -R option.
    Non-Admin users can only store their password if cygserver is running and
    the CYGWIN environment variable is set to contain the word 'server'.
    Note that storing even obfuscated passwords in the registry is not overly
    secure.  Use this feature only if the machine is adequately locked down.
    Don't use this feature if you don't need network access within a remote
    session.  You can delete your stored password by using `passwd -R' and
    specifying an empty password.

passwd changes passwords for user accounts. A normal user may only change the password for their own account, but administrators may change passwords on any account. passwd also changes account information, such as password expiry dates and intervals.

For password changes, the user is first prompted for their old password, if one is present. This password is then encrypted and compared against the stored password. The user has only one chance to enter the correct password. The administrators are permitted to bypass this step so that forgotten passwords may be changed.

The user is then prompted for a replacement password. passwd will prompt twice for this replacement and compare the second entry against the first. Both entries are required to match in order for the password to be changed.

After the password has been entered, password aging information is checked to see if the user is permitted to change their password at this time. If not, passwd refuses to change the password and exits.

To get current password status information, use the `-S` option. Administrators can use passwd to perform several account maintenance functions (users may perform some of these functions on their own accounts). Accounts may be locked with the `-l` flag and unlocked with the `-u` flag. Similarly, `-c` disables a user's ability to change passwords, and `-C` allows a user to change passwords. For password expiry, the `-e` option disables expiration, while the `-E` option causes the password to expire according to the system's normal aging rules. Use `-p` to disable the password requirement for a user, or `-P` to require a password.

Administrators can also use passwd to change system-wide password expiry and length requirements with the `-i`, `-n`, `-x`, and `-L` options. The `-i` option is used to disable an account after the password has been expired for a number of days. After a user account has had an expired password for NUM days, the user may no longer sign on to the account. The `-n` option is used to set the minimum number of days before a password may be changed. The user will not be permitted to change the password until MINDAYS days have elapsed. The `-x` option is used to set the maximum number of days a password remains valid. After MAXDAYS days, the password is required to be changed. Allowed values for the above options are 0 to 999. The `-L` option sets the minimum length of allowed passwords for users who don't belong to the administrators group to LEN characters. Allowed values for the minimum password length are 0 to 14. In any of the above cases, a value of 0 means `no restrictions'.

Users can use the passwd -R to enter a password which then gets stored in a special area of the registry, which is also used by Windows to store passwords of accounts running Windows services. When a privileged Cygwin application calls the set{e}uid(user_id) system call, Cygwin checks if a password for that user has been stored in this registry area. If so, it uses this password to switch to this user account using that password. This allows to logon through, for instance, ssh with public key authentication and to get a full qualified user token with all credentials for network access. However, the method has some drawbacks security-wise. This is explained in more detail in the the section called “Using Windows security in Cygwin” section.

Please note that storing password in that registry area is a privileged operation which only administrative accounts are allowed to do. If normal, non-admin users should be allowed to enter their passwords using passwd -R, it's required to run cygserver as a service under the LocalSystem account and the environment variable CYGWIN (see the section called “The CYGWIN environment variable”) must be set to contain the "server" setting before running passwd -R. This only affects storing passwords. Using passwords in privileged processes does not require cygserver to run.

Limitations: Users may not be able to change their password on some systems.

### ps

    Usage: ps [-aefls] [-u UID]
    Report process status

     -a, --all       show processes of all users
     -e, --everyone  show processes of all users
     -f, --full      show process uids, ppids
     -h, --help      output usage information and exit
     -l, --long      show process uids, ppids, pgids, winpids
     -p, --process   show information for specified PID
     -s, --summary   show process summary
     -u, --user      list processes owned by UID
     -v, --version   output version information and exit
     -W, --windows   show windows as well as cygwin processes
    With no options, ps outputs the long format by default

The ps program gives the status of all the Cygwin processes running on the system (ps = "process status"). Due to the limitations of simulating a POSIX environment under Windows, there is little information to give.

The PID column is the process ID you need to give to the kill command. The PPID is the parent process ID, and PGID is the process group ID. The WINPID column is the process ID displayed by NT's Task Manager program. The TTY column gives which pseudo-terminal a process is running on, or a `'?'` for services. The UID column shows which user owns each process. STIME is the time the process was started, and COMMAND gives the name of the program running. Listings may also have a status flag in column zero; `S` means stopped or suspended (in other words, in the background), `I` means waiting for input or interactive (foreground), and `O` means waiting to output.

By default ps will only show processes owned by the current user. With either the `-a` or `-e` option, all user's processes (and system processes) are listed. There are historical UNIX reasons for the synonomous options, which are functionally identical. The `-f` option outputs a "full" listing with usernames for UIDs. The `-l` option is the default display mode, showing a "long" listing with all the above columns. The other display option is `-s`, which outputs a shorter listing of just PID, TTY, STIME, and COMMAND. The `-u` option allows you to show only processes owned by a specific user. The `-p` option allows you to show information for only the process with the specified PID. The `-W` option causes ps show non-Cygwin Windows processes as well as Cygwin processes. The WINPID is also the PID, and they can be killed with the Cygwin kill command's `-f` option.

### regtool

    Usage: regtool [OPTION] (add|check|get|list|remove|unset|load|unload|save) KEY
    View or edit the Win32 registry

    Actions:
     add KEY\SUBKEY             add new SUBKEY
     check KEY                  exit 0 if KEY exists, 1 if not
     get KEY\VALUE              prints VALUE to stdout
     list KEY                   list SUBKEYs and VALUEs
     remove KEY                 remove KEY
     set KEY\VALUE [data ...]   set VALUE
     unset KEY\VALUE            removes VALUE from KEY
     load KEY\SUBKEY PATH       load hive from PATH into new SUBKEY
     unload KEY\SUBKEY          unload hive and remove SUBKEY
     save KEY\SUBKEY PATH       save SUBKEY into new hive PATH

    Options for 'list' Action:
     -k, --keys           print only KEYs
     -l, --list           print only VALUEs
     -p, --postfix        like ls -p, appends '\' postfix to KEY names

    Options for 'get' Action:
     -b, --binary         print REG_BINARY data as hex bytes

    Options for 'set' Action:
     -b, --binary         set type to REG_BINARY (hex args or '-')
     -e, --expand-string  set type to REG_EXPAND_SZ
     -i, --integer        set type to REG_DWORD
     -m, --multi-string   set type to REG_MULTI_SZ
     -s, --string         set type to REG_SZ

    Options for 'set' and 'unset' Actions:
     -K<c>, --key-separator[=]<c>  set key separator to <c> instead of '\'

    Other Options:
     -h, --help     output usage information and exit
     -q, --quiet    no error output, just nonzero return if KEY/VALUE missing
     -v, --verbose  verbose output, including VALUE contents when applicable
     -w, --wow64    access 64 bit registry view (ignored on 32 bit Windows)
     -W, --wow32    access 32 bit registry view (ignored on 32 bit Windows)
     -V, --version  output version information and exit

    KEY is in the format [host]\prefix\KEY\KEY\VALUE, where host is optional
    remote host in either \\hostname or hostname: format and prefix is any of:
      root     HKCR  HKEY_CLASSES_ROOT (local only)
      config   HKCC  HKEY_CURRENT_CONFIG (local only)
      user     HKCU  HKEY_CURRENT_USER (local only)
      machine  HKLM  HKEY_LOCAL_MACHINE
      users    HKU   HKEY_USERS

    You can use forward slash ('/') as a separator instead of backslash, in
    that case backslash is treated as escape character
    Example: regtool.exe get '\user\software\Microsoft\Clock\iFormat'

The regtool program allows shell scripts to access and modify the Windows registry. Note that modifying the Windows registry is dangerous, and carelessness here can result in an unusable system. Be careful.

The `-v` option means "verbose". For most commands, this causes additional or lengthier messages to be printed. Conversely, the `-q` option supresses error messages, so you can use the exit status of the program to detect if a key exists or not (for example).

The `-w` option allows to access the 64 bit view on the registry. Several subkeys exist in a 32 bit and a 64 bit version when running on Windows 64. Since Cygwin is running in 32 bit mode, it has only access to the 32 bit view of these registry keys. When using the `-w` the 64 bit view is used and regtool can access the entire registry. This option is simply ignored when running on 32 bit Windows versions.

The `-W` option allows to access the 32 bit view on the registry. The purpose of this option is mainly symmetry. It allows to create OS agnostic scripts which would also work in a hypothetic 64 bit version of Cygwin.

You must provide regtool with an action following options (if any). Currently, the action must be `add`, `set`, `check`, `get`, `list`, `remove`, `set`, or `unset`.

The `add` action adds a new key. The `check` action checks to see if a key exists (the exit code of the program is zero if it does, nonzero if it does not). The `get` action gets the value of a value of a key, and prints it (and nothing else) to stdout. Note: if the value doesn't exist, an error message is printed and the program returns a non-zero exit code. If you give `-q`, it doesn't print the message but does return the non-zero exit code.

The `list` action lists the subkeys and values belonging to the given key. With `list`, the `-k` option instructs regtool to print only KEYs, and the `-l` option to print only VALUEs. The `-p` option postfixes a `'/'` to each KEY, but leave VALUEs with no postfix. The `remove` action removes a key. Note that you may need to remove everything in the key before you may remove it, but don't rely on this stopping you from accidentally removing too much.

The `set` action sets a value within a key. `-b` means it's binary data (REG_BINARY). The binary values are specified as hex bytes in the argument list. If the argument is `'-'`, binary data is read from stdin instead. `-e` means it's an expanding string (REG_EXPAND_SZ) that contains embedded environment variables. `-i` means the value is an integer (REG_DWORD). `-m` means it's a multi-string (REG_MULTI_SZ). `-s` means the value is a string (REG_SZ). If you don't specify one of these, regtool tries to guess the type based on the value you give. If it looks like a number, it's a DWORD. If it starts with a percent, it's an expanding string. If you give multiple values, it's a multi-string. Else, it's a regular string. The `unset` action removes a value from a key.

The `load` action adds a new subkey and loads the contents of a registry hive into it. The parent key must be HKEY_LOCAL_MACHINE or HKEY_USERS. The `unload` action unloads the file and removes the subkey.

The `save` action saves a subkey into a registry hive.

By default, the last "\" or "/" is assumed to be the separator between the key and the value. You can use the `-K` option to provide an alternate key/value separator character.

### setfacl

    Usage: setfacl [-r] (-f ACL_FILE | -s acl_entries) FILE...
           setfacl [-r] ([-d acl_entries] [-m acl_entries]) FILE...
    Modify file and directory access control lists (ACLs)

      -d, --delete     delete one or more specified ACL entries
      -f, --file       set ACL entries for FILE to ACL entries read
                       from a ACL_FILE
      -m, --modify     modify one or more specified ACL entries
      -r, --replace    replace mask entry with maximum permissions
                       needed for the file group class
      -s, --substitute substitute specified ACL entries for the
                       ACL of FILE
      -h, --help       output usage information and exit
      -v, --version    output version information and exit

    At least one of (-d, -f, -m, -s) must be specified

For each file given as parameter, setfacl will either replace its complete ACL (`-s`, `-f`), or it will add, modify, or delete ACL entries. For more information on Cygwin and Windows ACLs, see see the section called “Using Windows security in Cygwin” in the Cygwin User's Guide.

Acl_entries are one or more comma-separated ACL entries from the following list:

             u[ser]::perm
             u[ser]:uid:perm
             g[roup]::perm
             g[roup]:gid:perm
             m[ask]::perm
             o[ther]::perm

Default entries are like the above with the additional default identifier. For example:

             d[efault]:u[ser]:uid:perm

perm is either a 3-char permissions string in the form "rwx" with the character `'-'` for no permission or it is the octal representation of the permissions, a value from 0 (equivalent to "---") to 7 ("rwx"). uid is a user name or a numerical uid. gid is a group name or a numerical gid.

The following options are supported:

`-d` Delete one or more specified entries from the file's ACL. The owner, group and others entries must not be deleted. Acl_entries to be deleted should be specified without permissions, as in the following list:

             u[ser]:uid
             g[roup]:gid
             d[efault]:u[ser]:uid
             d[efault]:g[roup]:gid
             d[efault]:m[ask]:
             d[efault]:o[ther]:

`-f` Take the Acl_entries from ACL_FILE one per line. Whitespace characters are ignored, and the character "#" may be used to start a comment. The special filename "-" indicates reading from stdin. Note that you can use this with getfacl and setfacl to copy ACLs from one file to another:

    $ getfacl source_file | setfacl -f - target_file

Required entries are: one user entry for the owner of the file, one group entry for the group of the file, and one other entry.

If additional user and group entries are given: a mask entry for the file group class of the file, and no duplicate user or group entries with the same uid/gid.

If it is a directory: one default user entry for the owner of the file, one default group entry for the group of the file, one default mask entry for the file group class, and one default other entry.

`-m` Add or modify one or more specified ACL entries. Acl_entries is a comma-separated list of entries from the same list as above.

`-r` Causes the permissions specified in the mask entry to be ignored and replaced by the maximum permissions needed for the file group class.

`-s` Like `-f`, but substitute the file's ACL with Acl_entries specified in a comma-separated list on the command line.

While the `-d` and `-m` options may be used in the same command, the `-f` and `-s` options may be used only exclusively.

Directories may contain default ACL entries. Files created in a directory that contains default ACL entries will have permissions according to the combination of the current umask, the explicit permissions requested and the default ACL entries

Limitations: Under Cygwin, the default ACL entries are not taken into account currently.

### ssp

    Usage: ssp [options] low_pc high_pc command...
    Single-step profile COMMAND

     -c, --console-trace  trace every EIP value to the console. *Lots* slower.
     -d, --disable        disable single-stepping by default; use
                          OutputDebugString ("ssp on") to enable stepping
     -e, --enable         enable single-stepping by default; use
                          OutputDebugString ("ssp off") to disable stepping
     -h, --help           output usage information and exit
     -l, --dll            enable dll profiling.  A chart of relative DLL usage
                          is produced after the run.
     -s, --sub-threads    trace sub-threads too.  Dangerous if you have
                          race conditions.
     -t, --trace-eip      trace every EIP value to a file TRACE.SSP.  This
                          gets big *fast*.
     -v, --verbose        output verbose messages about debug events.
     -V, --version        output version information and exit

    Example: ssp 0x401000 0x403000 hello.exe

SSP - The Single Step Profiler

Original Author: DJ Delorie

The SSP is a program that uses the Win32 debug API to run a program one ASM instruction at a time. It records the location of each instruction used, how many times that instruction is used, and all function calls. The results are saved in a format that is usable by the profiling program gprof, although gprof will claim the values are seconds, they really are instruction counts. More on that later.

Because the SSP was originally designed to profile the cygwin DLL, it does not automatically select a block of code to report statistics on. You must specify the range of memory addresses to keep track of manually, but it's not hard to figure out what to specify. Use the "objdump" program to determine the bounds of the target's ".text" section. Let's say we're profiling cygwin1.dll. Make sure you've built it with debug symbols (else gprof won't run) and run objdump like this:

    $ objdump -h cygwin1.dll

It will print a report like this:

    cygwin1.dll:     file format pei-i386

    Sections:
    Idx Name          Size      VMA       LMA       File off  Algn
      0 .text         0007ea00  61001000  61001000  00000400  2**2
                      CONTENTS, ALLOC, LOAD, READONLY, CODE, DATA
      1 .data         00008000  61080000  61080000  0007ee00  2**2
                      CONTENTS, ALLOC, LOAD, DATA
      . . .

The only information we're concerned with are the VMA of the .text section and the VMA of the section after it (sections are usually contiguous; you can also add the Size to the VMA to get the end address). In this case, the VMA is 0x61001000 and the ending address is either 0x61080000 (start of .data method) or 0x0x6107fa00 (VMA+Size method).

There are two basic ways to use SSP - either profiling a whole program, or selectively profiling parts of the program.

To profile a whole program, just run ssp without options. By default, it will step the whole program. Here's a simple example, using the numbers above:

    $ ssp 0x61001000 0x61080000 hello.exe

This will step the whole program. It will take at least 8 minutes on a PII/300 (yes, really). When it's done, it will create a file called "gmon.out". You can turn this data file into a readable report with gprof:

    $ gprof -b cygwin1.dll

The "-b" means 'skip the help pages'. You can omit this until you're familiar with the report layout. The gprof documentation explains a lot about this report, but ssp changes a few things. For example, the first part of the report reports the amount of time spent in each function, like this:

    Each sample counts as 0.01 seconds.
      %   cumulative   self              self     total
     time   seconds   seconds    calls  ms/call  ms/call  name
     10.02    231.22    72.43       46  1574.57  1574.57  strcspn
      7.95    288.70    57.48      130   442.15   442.15  strncasematch

The "seconds" columns are really CPU opcodes, 1/100 second per opcode. So, "231.22" above means 23,122 opcodes. The ms/call values are 10x too big; 1574.57 means 157.457 opcodes per call. Similar adjustments need to be made for the "self" and "children" columns in the second part of the report.

OK, so now we've got a huge report that took a long time to generate, and we've identified a spot we want to work on optimizing. Let's say it's the time() function. We can use SSP to selectively profile this function by using OutputDebugString() to control SSP from within the program. Here's a sample program:

    	#include <windows.h>
    	main()
    	{
    	  time_t t;
    	  OutputDebugString("ssp on");
    	  time(&t);
    	  OutputDebugString("ssp off");
    	}

Then, add the `-d` option to ssp to default to *disabling* profiling. The program will run at full speed until the first OutputDebugString, then step until the second. You can then use gprof (as usual) to see the performance profile for just that portion of the program's execution.

There are many options to ssp. Since step-profiling makes your program run about 1,000 times slower than normal, it's best to understand all the options so that you can narrow down the parts of your program you need to single-step.

`-v` - verbose. This prints messages about threads starting and stopping, OutputDebugString calls, DLLs loading, etc.

`-t` and `-c` - tracing. With `-t`, *every* step's address is written to the file "trace.ssp". This can be used to help debug functions, since it can trace multiple threads. Clever use of scripts can match addresses with disassembled opcodes if needed. Warning: creates *huge* files, very quickly. `-c` prints each address to the console, useful for debugging key chunks of assembler. Use `addr2line -C -f -s -e foo.exe < trace.ssp > lines.ssp` and then `perl cvttrace` to convert to symbolic traces.

`-s` - subthreads. Usually, you only need to trace the main thread, but sometimes you need to trace all threads, so this enables that. It's also needed when you want to profile a function that only a subthread calls. However, using OutputDebugString automatically enables profiling on the thread that called it, not the main thread.

`-l` - dll profiling. Generates a pretty table of how much time was spent in each dll the program used. No sense optimizing a function in your program if most of the time is spent in the DLL. I usually use the `-v`, `-s`, and `-l` options:

    $ ssp -v -s -l -d 0x61001000 0x61080000 hello.exe

### strace

    Usage: strace.exe [OPTIONS] <command-line>
    Usage: strace.exe [OPTIONS] -p <pid>
    Trace system calls and signals

      -b, --buffer-size=SIZE       set size of output file buffer
      -d, --no-delta               don't display the delta-t microsecond timestamp
      -f, --trace-children         trace child processes (toggle - default true)
      -h, --help                   output usage information and exit
      -m, --mask=MASK              set message filter mask
      -n, --crack-error-numbers    output descriptive text instead of error
                                   numbers for Windows errors
      -o, --output=FILENAME        set output file to FILENAME
      -p, --pid=n                  attach to executing program with cygwin pid n
      -q, --quiet                  toggle "quiet" flag.  Defaults to on if "-p",
                                   off otherwise.
      -S, --flush-period=PERIOD    flush buffered strace output every PERIOD secs
      -t, --timestamp              use an absolute hh:mm:ss timestamp insted of
                                   the default microsecond timestamp.  Implies -d
      -T, --toggle                 toggle tracing in a process already being
      -u, --usecs                  toggle printing of microseconds timestamp
                                   traced. Requires -p <pid>
      -v, --version                output version information and exit
      -w, --new-window             spawn program under test in a new window

        MASK can be any combination of the following mnemonics and/or hex values
        (0x is optional).  Combine masks with '+' or ',' like so:

                          --mask=wm+system,malloc+0x00800

        Mnemonic Hex     Corresponding Def  Description
        =========================================================================
        all      0x00001 (_STRACE_ALL)      All strace messages.
        flush    0x00002 (_STRACE_FLUSH)    Flush output buffer after each message.
        inherit  0x00004 (_STRACE_INHERIT)  Children inherit mask from parent.
        uhoh     0x00008 (_STRACE_UHOH)     Unusual or weird phenomenon.
        syscall  0x00010 (_STRACE_SYSCALL)  System calls.
        startup  0x00020 (_STRACE_STARTUP)  argc/envp printout at startup.
        debug    0x00040 (_STRACE_DEBUG)    Info to help debugging.
        paranoid 0x00080 (_STRACE_PARANOID) Paranoid info.
        termios  0x00100 (_STRACE_TERMIOS)  Info for debugging termios stuff.
        select   0x00200 (_STRACE_SELECT)   Info on ugly select internals.
        wm       0x00400 (_STRACE_WM)       Trace Windows msgs (enable _strace_wm).
        sigp     0x00800 (_STRACE_SIGP)     Trace signal and process handling.
        minimal  0x01000 (_STRACE_MINIMAL)  Very minimal strace output.
        exitdump 0x04000 (_STRACE_EXITDUMP) Dump strace cache on exit.
        system   0x08000 (_STRACE_SYSTEM)   Serious error; goes to console and log.
        nomutex  0x10000 (_STRACE_NOMUTEX)  Don't use mutex for synchronization.
        malloc   0x20000 (_STRACE_MALLOC)   Trace malloc calls.
        thread   0x40000 (_STRACE_THREAD)   Thread-locking calls.

The strace program executes a program, and optionally the children of the program, reporting any Cygwin DLL output from the program(s) to stdout, or to a file with the `-o` option. With the `-w` option, you can start an strace session in a new window, for example:

    $ strace -o tracing_output -w sh -c 'while true; do echo "tracing..."; done' &

This is particularly useful for strace sessions that take a long time to complete.

Note that strace is a standalone Windows program and so does not rely on the Cygwin DLL itself (you can verify this with cygcheck). As a result it does not understand symlinks. This program is mainly useful for debugging the Cygwin DLL itself.

### umount

    Usage: umount.exe [OPTION] [<posixpath>]
    Unmount filesystems

      -h, --help                    output usage information and exit
      -U, --remove-user-mounts      remove all user mounts
      -v, --version                 output version information and exit

The umount program removes mounts from the mount table in the current session. If you specify a POSIX path that corresponds to a current mount point, umount will remove it from the current mount table. Note that you can only remove user mount points. The `-U` flag may be used to specify removing all user mount points from the current user session.

See the section called “The Cygwin Mount Table” for more information on the mount table.

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