Cd (command)

The cd command, also known as chdir (change directory), is a command-line OS shell command used to change the current working directory in operating systems such as Unix, DOS, OS/2, AmigaOS (where if a bare path is given, cd is implied), Windows, and Linux. It is also available for use in shell scripts and batch files. The system call that affects the command in most operating systems is chdir that is defined by POSIX.

A directory is a logical section of a file system used to hold files. Directories may also contain other directories. The cd command can be used to change into a subdirectory, move back into the parent directory, move all the way back to the root directory or move to any given directory.

Consider the following subsection of a Unix filesystem, which shows a user's home directory (represented as “~”) with a file (“text.txt”) and three subdirectories.

If the user's current working directory is the home directory (“~”), then entering the command ls followed by cd games might produce the following transcript:

The user is now in the “games” directory.

A similar session in DOS (though the concept of a “home directory” may not apply, depending on the specific version) would look like this:

DOS maintains separate working directories for each lettered drive, and also has the concept of a current working drive. The cd command can be used to change the working directory of the working drive or another lettered drive. Typing the drive letter as a command on its own changes the working drive, e.g. C:; alternatively, cd with the /d switch may be used to change the working drive and that drive's working directory in one step. Modern versions of Windows simulate this behaviour for backwards compatibility under CMD.EXE.

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