Commands

target_directory

Change directory. This command makes target_directory your current working directory. It is a strong contender for the single most commonly used command in Linux. target_directory may be either a relative path, an absolute path, a shell symbol, or a shell variable.

Example: In the examples on the usage of the cd command presented next, assume that the shell variable $BOB stands for /home/bob. The directory tree is the same as the sample directory tree printed in the front of this chapter:

Starting Directory	target_directory Type	Example Command	Ending Directory
/home/shawkins	relative	cd linux	/home/shawkins/linux
/home/shawkins	absolute	cd /home	/home
/home/shawkins	shell symbol	cd ..	/home
/home/shawkins	shell variable	cd $BOB	/home/bob

mkdir

[OPTION] NAME

Create a directory.

Example: To create a new directory called tcl_stuff under your current working directory, use

mkdir tcl_stuff

Example: To create a new directory called tcl_stuff under your current working directory with read, write, and execute permissions for the owner, but no permissions for anyone else, use

mkdir -m 700 tcl_stuff

`-m MODE, --mode=MODE`	Set the file permissions as specified.
`-p, --parents`	Make any missing parent directories for each argument.
`--verbose`	Verbose output. Display a message for each directory created.

pwd

Display the fully resolved name (i.e., the full pathname starting at the root directory) of the current directory.

Example: To display the current directory, use

pwd

rmdir

[OPTION] DIRECTORY

Remove the specified directory(ies). All directories specified must (a) exist and (b) be empty.

Example: To remove the directory tcl_stuff, use

rmdir tcl_stuff

Example: To remove the directory tcl_stuff and any empty parent directories it may have, use

rmdir -p tcl_stuff

-p, --parents

Tell rmdir to remove any parent directories that may become empty after one of the subdirectories is removed.

symlinks

[ -cdrv ] dirlist

This command scans directories for symbolic links, listing them to standard output. Each link is classified as one of the following:

`relative`	A link expressed as a path relative to the directory in which the link resides.
`absolute`	A link given as an absolute path from the root directory.
`dangling`	A link whose target does not currently exist.
`messy`	A link containing unnecessary slashes or dots in the path.
`lengthy`	A length using "../" more than necessary in the path.
`other_fs`	A link whose target resides on a different filesystem.

Example: To search all the subdirectories under your home directory (-r option) for symbolic links, removing any dangling links found (-d option), use

symlinks -r -d ~

`-c`	Convert absolute links to relative links.
`-d`	Remove dangling links.
`-r`	Recursive operation (within a single filesystem).
`-s`	Detach lengthy links.
`-t`	Test what would happen if -c was specified but don't change anything.
`-v`	Include relative links in the output. (By default, they are excluded.)