rm (short for remove) is a basic command on Unix and Unix-like operating systems used to remove objects such as computer files, directories and symbolic links from file systems and also special files such as device nodes, pipes and sockets, similar to the del command in MS-DOS, OS/2, and Microsoft Windows. The command is also available in the EFI shell.
Overview
The rm command removes references to objects from the filesystem using the unlink system call, where those objects might have had multiple references (for example, a file with two different names), and the objects themselves are discarded only when all references have been removed and no programs still have open handles to the objects.
This allows for scenarios where a program can open a file, immediately remove it from the filesystem, and then use it for temporary space, knowing that the file's space will be reclaimed after the program exits, even if it exits by crashing.
The command generally does not destroy file data, since its purpose is really merely to unlink references, and the filesystem space freed may still contain leftover data from the removed file. This can be a security concern in some cases, and hardened versions sometimes provide for wiping out the data as the last link is being cut, and programs such as shred and srm are available which specifically provide data wiping capability.
rm is generally only seen on UNIX-derived operating systems, which typically do not provide for recovery of deleted files through a mechanism like the recycle bin, hence the tendency for users to enclose rm in some kind of wrapper to limit accidental file deletion.
There are undelete utilities that will attempt to reconstruct the index and can bring the file back if the parts were not reused.
History
On some old versions of Unix, the rm command would delete directories if they were empty. This behaviour can still be obtained in some versions of rm with the -d flag, e.g., the BSDs (such as FreeBSD, NetBSD, OpenBSD and macOS) derived from 4.4BSD-Lite2.
The version of rm bundled in GNU coreutils was written by Paul Rubin, David MacKenzie, Richard Stallman, and Jim Meyering. This version also provides -d option, to help with compatibility. The same functionality is provided by the standard rmdir command.
The -i option in Version 7 replaced dsw, or "delete from switches", which debuted in Version 1. Doug McIlroy wrote that dsw "was a desperation tool designed to clean up files with unutterable names".
The command is available as a separate package for Microsoft Windows as part of the UnxUtils collection of native Win32 ports of common GNU Unix-like utilities. KolibriOS includes an implementation of the command. The command has also been ported to the IBM i operating system.
Syntax
rm deletes the file specified after options are added. Users can use a full path or a relative file path to specify the files to delete. rm doesn't delete a directory by default.rm foo deletes the file "foo" in the directory the user is currently in.
rm, like other commands, uses options to specify how it will behave:
-r, "recursive," which removes directories, removing the contents recursively beforehand (so as not to leave files without a directory to reside in). -i, "interactive" which asks for every deletion to be confirmed. -f, "force," which ignores non-existent files and overrides any confirmation prompts (effectively canceling -i), although it will not remove files from a directory if the directory is write-protected. -v, "verbose," which prints what rm is doing onto the terminal -d, "directory," which deletes an empty directory, and only works if the specified directory is empty. --one-file-system, only removes files on the same file system as the argument, and will ignore mounted file systems.
rm can be overlain by a shell alias (C shell alias, Bourne shell or Bash) function of "rm -i" so as to avoid accidental deletion of files. If a user still wishes to delete a large number of files without confirmation, they can manually cancel out the -i argument by adding the -f option (as the option specified later on the expanded command line "rm -i -f" takes precedence). Unfortunately this approach generates dangerous habits towards the use of wildcarding, leading to its own version of accidental removals.
rm -rf (variously, rm -rf /, rm -rf *, and others) is frequently used in jokes and anecdotes about Unix disasters, such as the loss of many files during the production of film Toy Story 2 at Pixar. The rm -rf / variant of the command, if run by a superuser, would cause every file accessible from the present file system to be deleted from the machine.