When executed it invokes a shell without changing the current working directory or the user environment.

[5] 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.

[6] The su command was removed from GNU coreutils as of release 8.18 (2012-08-12)[7] and is currently included in the util-linux package.

When run from the command line, su asks for the target user's password, and if authenticated, grants the operator access to that account and the files and directories that account is permitted to access.

Some Unix-like systems implement the user group wheel, and only allow members to become root with su.