bin/timeout/timeout.1

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.\" Copyright (c) 2014 Baptiste Daroussin <bapt@FreeBSD.org>
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.Dd April 3, 2025
.Dt TIMEOUT 1
.Os
.Sh NAME
.Nm timeout
.Nd run a command with a time limit
.Sh SYNOPSIS
.Nm
.Op Fl f | Fl -foreground
.Op Fl k Ar time | Fl -kill-after Ar time
.Op Fl p | Fl -preserve-status
.Op Fl s Ar signal | Fl -signal Ar signal
.Op Fl v | Fl -verbose
.Ar duration
.Ar command
.Op Ar arg ...
.Sh DESCRIPTION
.Nm Timeout
starts the
.Ar command
with its
.Ar arg
list.
If the
.Ar command
is still running after
.Ar duration ,
it is killed by sending the
.Ar signal ,
or
.Dv SIGTERM
if the
.Fl s
option is unspecified.
The special
.Ar duration ,
zero, signifies no limit.
Therefore, a signal is never sent if
.Ar duration
is 0.
.Pp
The signal dispositions inherited by the
.Ar command
are the same as the dispositions that
.Nm
inherited, except for the signal that will be sent upon timeout,
which is reset to take the default action and should terminate
the process.
.Pp
If
.Nm
receives the
.Dv SIGALRM
signal, it will behave as if the time limit has been reached
and send the specified signal to
.Ar command .
For any other signals delivered to
.Nm ,
it will propagate them to
.Ar command ,
with the exception of
.Dv SIGKILL
and
.Dv SIGSTOP .
If you want to prevent the
.Ar command
from being timed out, send
.Dv SIGKILL
to
.Nm .
.Pp
The options are as follows:
.Bl -tag -width indent
.It Fl f , Fl -foreground
Only time out the
.Ar command
itself, but do not propagate signals to its descendants.
.It Fl k Ar time , Fl -kill-after Ar time
Send a
.Dv SIGKILL
signal if
.Ar command
is still running after
.Ar time
since the first signal was sent.
.It Fl p , Fl -preserve-status
Always exit with the same status as
.Ar command ,
even if the timeout was reached.
.It Fl s Ar signal , Fl -signal Ar signal
Specify the signal to send on timeout.
By default,
.Dv SIGTERM
is sent.
.It Fl v , Fl -verbose
Show information to
.Xr stderr 4
about timeouts, signals to be sent, and the
.Ar command
exits.
.El
.Ss Duration Format
The
.Ar duration
and
.Ar time
are non-negative integer or real (decimal) numbers, with an optional
suffix specifying the unit.
Values without an explicit unit are interpreted as seconds.
.Pp
Supported unit suffixes are:
.Bl -tag -offset indent -width indent -compact
.It Cm s
seconds
.It Cm m
minutes
.It Cm h
hours
.It Cm d
days
.El
.Sh EXIT STATUS
If the timeout was not reached, the exit status of
.Ar command
is returned.
.Pp
If the timeout was reached and
.Fl -preserve-status
is set, the exit status of
.Ar command
is returned.
If
.Fl -preserve-status
is not set, an exit status of 124 is returned.
.Pp
If an invalid parameter is passed to
.Fl s
or
.Fl k ,
the exit status returned is 125.
.Pp
If
.Ar command
is an otherwise invalid program, the exit status returned is 126.
.Pp
If
.Ar command
refers to a non-existing program, the exit status returned is 127.
.Pp
If
.Ar command
exits after receiving a signal, the exit status returned is the signal number
plus 128.
.Sh EXAMPLES
Run
.Xr sleep 1
with a time limit of 4 seconds.
Since the command completes in 2 seconds, the exit status is 0:
.Bd -literal -offset indent
$ timeout 4 sleep 2
$ echo $?
0
.Ed
.Pp
Run
.Xr sleep 1
for 4 seconds and terminate process after 2 seconds.
The exit status is 124 since
.Fl -preserve-status
is not used:
.Bd -literal -offset indent
$ timeout 2 sleep 4
$ echo $?
124
.Ed
.Pp
Same as above but preserving status.
The exit status is 128 + signal number (15 for
.Dv SIGTERM ) :
.Bd -literal -offset indent
$ timeout --preserve-status 2 sleep 4
$ echo $?
143
.Ed
.Pp
Same as above but sending
.Dv SIGALRM
(signal number 14) instead of
.Dv SIGTERM :
.Bd -literal -offset indent
$ timeout --preserve-status -s SIGALRM 2 sleep 4
$ echo $?
142
.Ed
.Pp
Try to
.Xr fetch 1
the PDF version of the
.Fx
Handbook.
Send a
.Dv SIGTERM
signal after 1 minute and send a
.Dv SIGKILL
signal 5 seconds later if the process refuses to stop:
.Bd -literal -offset indent
$ timeout -k 5s 1m fetch \\
> https://download.freebsd.org/ftp/doc/en/books/handbook/book.pdf
.Ed
.Sh SEE ALSO
.Xr kill 1 ,
.Xr nohup 1 ,
.Xr signal 3 ,
.Xr daemon 8
.Sh STANDARDS
The
.Nm
utility is expected to conform to the
.St -p1003.1-2024
specification.
.Sh HISTORY
The
.Nm
command first appeared in
.Fx 10.3 .
.Pp
The
.Fx
work is compatible with GNU
.Nm
by
.An Padraig Brady ,
from GNU Coreutils 8.21.
The
.Nm
utility first appeared in GNU Coreutils 7.0.
.Sh AUTHORS
.An Baptiste Daroussin Aq Mt bapt@FreeBSD.org
and
.An Vsevolod Stakhov Aq Mt vsevolod@FreeBSD.org