Usage
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:
C:\> dir workreportsDOS 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.
Note that executing cd from the command line with no arguments has different effects in different operating systems. For example, if cd is executed without arguments in DOS, OS/2, or Windows, the current working directory is displayed. If cd is executed without arguments in Unix, the user is returned to the home directory.
Executing the cd command within a script or batch file also has different effects in different operating systems. In DOS, the caller's current directory can be directly altered by the batch file's use of this command. In Unix, the caller's current directory is not altered by the script's invocation of the cd command. This is because in Unix, the script is usually executed within a subshell.
Read more about this topic: Cd (command)
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