path: root/bin/timeout/timeout.1

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.\" Copyright (c) 2014 Baptiste Daroussin <bapt@FreeBSD.org>
.\" Copyright (c) 2025 Aaron LI <aly@aaronly.me>
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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.
See the
.Sx IMPLEMENTATION NOTES
section for more details.
.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 IMPLEMENTATION NOTES
If the
.Fl -foreground
option is not specified,
.Nm
runs as the reaper (see also
.Xr procctl 2 )
of the
.Ar command
and its descendants, and will wait for all the descendants to terminate.
This behavior might cause surprises if there are descendants running
in the background, because they will ignore
.Dv SIGINT
and
.Dv SIGQUIT
signals.
For example, the following command that sends a
.Dv SIGTERM
signal will complete in 2 seconds:
.Dl $ timeout -s TERM 2 sh -c 'sleep 4 & sleep 5'
However, this command that sends a
.Dv SIGINT
signal will complete in 4 seconds:
.Dl $ timeout -s INT 2 sh -c 'sleep 4 & sleep 5'
.Sh EXIT STATUS
If the time limit was reached and the
.Fl -preserve-status
option is not specified, the exit status is 124.
Otherwise,
.Nm
exits with the same exit status as the
.Ar command .
For example,
.Nm
will terminate itself with the same signal if the
.Ar command
is terminated by a signal.
.Pp
If an error occurred, the following exit values are returned:
.Bl -tag -offset indent with indent -compact
.It 125
An error other than the two described below occurred.
For example, an invalid duration or signal was specified.
.It 126
The
.Ar command
was found but could not be executed.
.It 127
The
.Ar command
could not be found.
.El
.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 )
for most shells:
.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 initial
.Fx
work was 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 ,
.An Vsevolod Stakhov Aq Mt vsevolod@FreeBSD.org
and
.An Aaron LI Aq Mt aly@aaronly.me