If you just type mount with no parameters, it will display the current mount table for you.
c:\cygwin\> mount
c:\cygwin\bin on /usr/bin type system (binmode)
c:\cygwin\lib on /usr/lib type system (binmode)
c:\cygwin on / type system (binmode)
c: on /c type user (binmode,noumount)
d: on /d type user (binmode,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.
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 sytem (binmode)
c:\cygwin\bin on /usr/bin type system (binmode)
c:\cygwin\lib on /usr/lib type system (binmode)
c:\cygwin on / type system (binmode)
c: on /c type user (binmode,noumount)
d: on /d type user (binmode,noumount)
Note that mount was invoked from the Windows command shell in the previous example. In many Unix shells, including bash, it is legal and convenient to use the forward "/" in Win32 pathnames since the "\" is the shell's escape character.
The -s flag to mount is used to add a mount in the system-wide mount table used by all Cygwin users on the system, instead of the user-specific one. System-wide mounts are displayed by mount as being of the "system" type, as is the case for the / partition in the last example. Under Windows NT, only those users with Administrator priviledges are permitted to modify the system-wide mount table.
Note that a given POSIX path may only exist once in the user table and once in the global, system-wide table. Attempts to replace the mount will fail with a busy error. The -f (force) flag causes the old mount to be silently replaced with the new one. It will also silence warnings about the non-existence of directories at the Win32 path location.
The -b flag is used to instruct Cygwin to treat binary and text files in the same manner by default. Binary mode mounts are marked as "binmode" in the Flags column of mount output. By default, mounts are in text mode ("textmode" in the Flags column).
Normally, files ending in certain extensions (.exe, .com, .bat, .cmd) are assumed to be executable. Files whose first two characters begin with '#!' are also considered to be executable. The -x flag is used to instruct Cygwin that the mounted file is "executable". If the -x flag is used with a directory then all files in the directory are executable. This option allows other files to be marked as executable and avoids the overhead of opening each file to check for a '#!'. The -X option is very similar to -x, but also prevents Cygwin from setting up commands and environment variables for a normal Windows program, adding another small performance gain. The opposite of these flags is the -E flag, which means that no files should be marked as executable.
The -m option causes the mount utility to output a series of commands that could recreate both user and system mount points. You can save this output as a backup when experimenting with the mount table. It also makes moving your settings to a different machine much easier.
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):
user - mount lives user-specific mount
system - mount lives in system table (default)
binary - files default to binary mode (default)
text - files default to CRLF text mode line endings
exec - files below mount point are all executable
notexec - files below mount point are not executable
cygexec - files below mount point are all cygwin executables
nosuid - no suid files are allowed (currently unimplemented)
managed - directory is managed by cygwin. Mixed case and special
characters in filenames are allowed.
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 /:
c:\cygwin\> mount --change-cygdrive-prefix /
Note that if you set a new prefix in this manner, you can specify the -s flag to make this the system-wide default prefix. By default, the cygdrive-prefix applies only to the system-wide setting. 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: 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.
Cygwin is Free software; for complete licensing information, refer to:
http://cygwin.com/licensing.html
The full documentation to the Cygwin Utilities is maintained on the web at:
http://cygwin.com/cygwin-ug-net/using-utils.html
The website is updated more frequently than the man pages and should be considered the authoritative source of information.