man pages: document `--user` option for `runuser`

Signed-off-by: Christoph Anton Mitterer <mail@christoph.anton.mitterer.name>
(cherry picked from commit 2a562a5f5f56f6afb87ee7521f486248cb21aab6)

diff --git a/login-utils/runuser.1.adoc b/login-utils/runuser.1.adoc
index b128c198419c0149dc14a8d63329ce0b0c925575..b041572e1020fa2af44883d56a26b3eecbd538fb 100644 (file)
--- a/login-utils/runuser.1.adoc
+++ b/login-utils/runuser.1.adoc
@@ -77,6 +77,9 @@ Same as *-c*, but do not create a new session. (Discouraged.)
 Do not create a pseudo-terminal, opposite of *--pty* and *-P*.
 Note that running without a pseudo-terminal opens the security risk of privilege escalation through TIOCSTI/TIOCLINUX ioctl command injection.
 
+*-u*, *--user*=_user_::
+Run _command_ with the effective user ID and group ID of the user name _user_.
+
 *-w*, *--whitelist-environment*=_list_::
 Don't reset the environment variables specified in the comma-separated _list_ when clearing the environment for *--login*. The whitelist is ignored for the environment variables *HOME*, *SHELL*, *USER*, *LOGNAME*, and *PATH*.