.Dd 2023-08-13
.Dt CRONTAB 1
.Os systemd-cron 2.3.4-1
.
.Sh NAME
.Nm crontab
.Nd maintain crontab files for individual users
.
.Sh SYNOPSIS
.Nm
.Op Fl u Ar user
.Op Ar newtab
.
.Nm
.Fl l
.Op Fl u Ar user
.
.Nm
.Fl r
.Op Fl i
.Op Fl u Ar user
.
.Nm
.Fl e
.Op Fl u Ar user
.
.Nm
.Fl s
.
.Nm
.Fl t
.Ar line
.
.Nm
.Fl T
.Ar crontab
.
.Sh DESCRIPTION
.Nm
lets users install, uninstall, view, and edit recurrent jobs in the
.Xr crontab 5
format,
as well as pre-view and convert them to
.Xr systemd.timer 5
pairs.
root may also spy on who which users have installed crontabs.
.Pp
.\" Assumes DEFAULT_NOACCESS=0
Each user may have their own crontab, but this can be limited by
.Pa /etc/cron.allow
to create an explicit allow-list or
.Pa /etc/cron.deny
to deny access to individual users.
.Pp
Crontabs are checked before installing \(em
if they are found to be invalid, installation is aborted and a summary of errors is written to the standard error stream.
.
.Sh OPTIONS
.Bl -tag -compact -width ".Fl u , -user Ns = Ns Ar user"
.It (by default)
replace the user's crontab from
.Ar newtab
.Pq standard input stream if Qo Sy - Qc , the default .
.
.It Fl l , -list
Copy user's crontab to the standard output stream, or error if there is none.
.
.It Fl r , -remove
Remove user's crontab.
.It Fl i , -ask
Output a confirmation prompt before doing so.
.
.It Fl e , -edit
Let user edit crontab, install when they're done.
.
.It Fl s , -show
List which users have a crontab installed.
Nonexistent users are warned about to the standard error stream.
Only root can do this.
.
.It Fl t , -translate
Validate and translate a
.Xr crontab 5
.Ar line
into a native
.Xr systemd.timer 5
pair to the standard output stream.
.
.It Fl T , -test
Validate whether
.Ar crontab
is a valid
.Xr crontab 5
file.
.Pp
.
.It Fl u , -user Ns = Ns Ar user
Edit
.Ar user Ns 's
crontab instead of the currently-logged-in user's.
Only root can do this, and they should be careful about using
.Nm
without this option \(em the current user is determined by
.Pf $ Ev LOGNAME ,
.Pf $ Ev USER ,
.Pf $ Ev LNAME
.Pf $ Ev USERNAME ,
and only then by the real UID!
.El
.
.Sh FILES
.Bl -tag -compact -width ".Pa /var/spool/cron/crontabs"
.\" Assumes DEFAULT_NOACCESS=0
.It Pa /etc/cron.allow
If exists, only users listed here (one username per line) can install their own crontabs.
Otherwise, everyone can.
.
.It Pa /etc/cron.deny
Users listed here aren't allowed to install their own crontabs.
.
.It Pa /var/spool/cron/crontabs
Crontabs live here.
.El
.
.Sh ENVIRONMENT
.Ev EDITOR ,
.Ev VISUAL ,
.Nm editor ,
.Nm vim ,
.Nm nano ,
and
.Nm mcedit
are tried, in order, when using
.Fl e .
.
.Sh SEE ALSO
.Xr crontab 5 ,
.Xr systemd.cron 7
for a summary of the format and how to tweak installed cronjobs \(em
.Nm systemctl Cm edit Li cron- Ns Ar schedule Ns Li .\& Ns Brq Li timer Ns |\& Ns Li service .
.
.Sh LIMITATIONS
SELinux is not supported.
.
.\".Sh AUTHOR
.\".An -split
.\".An Konstantin Stepanov Aq Mt me@kstep.me
.\".An Alexandre Detiste Aq Mt alexandre@detiste.be
.\"\(em manual and setgid helper