freebsd-dev/usr.bin/time/time.1

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.\"     @(#)time.1	8.1 (Berkeley) 6/6/93
.\" $FreeBSD$
.\"
.Dd July 7, 2020
.Dt TIME 1
.Os
.Sh NAME
.Nm time
.Nd time command execution
.Sh SYNOPSIS
.Nm
.Op Fl al
.Op Fl h | Fl p
.Op Fl o Ar file
.Ar utility Op Ar argument ...
.Sh DESCRIPTION
The
.Nm
utility
executes and
times the specified
.Ar utility .
After the
.Ar utility
finishes,
.Nm
writes to the standard error stream,
(in seconds):
the total time elapsed,
the time used to execute the
.Ar utility
process and the time consumed by system overhead.
.Pp
The following options are available:
.Bl -tag -width indent
.It Fl a
If the
.Fl o
flag is used, append to the specified file rather than overwriting
it.
Otherwise, this option has no effect.
.It Fl h
Print times in a human friendly format.
Times are printed in minutes, hours,
etc.\& as appropriate.
.It Fl l
The contents of the
.Em rusage
structure are printed as well.
.It Fl o Ar file
Write the output to
.Ar file
instead of stderr.
If
.Ar file
exists and the
.Fl a
flag is not specified, the file will be overwritten.
.It Fl p
Makes
.Nm
output POSIX.2 compliant (each time is printed on its own line).
.El
.Pp
Some shells may provide a builtin
.Nm
command which is similar or identical to this utility.
Consult the
.Xr builtin 1
manual page.
.Pp
If
.Nm
receives a
.Dv SIGINFO
(see the status argument for
.Xr stty 1 )
signal, the current time the given command is running will be written to the
standard output.
.Sh ENVIRONMENT
The
.Ev PATH
environment variable is used to locate the requested
.Ar utility
if the name contains no
.Ql /
characters.
.Sh EXIT STATUS
If
.Ar utility
could be timed successfully, its exit status is returned.
If
.Ar utility
terminated abnormally, a warning message is output to stderr.
If the
.Ar utility
was found but could not be run, the exit status is 126.
If no
.Ar utility
could be found at all, the exit status is 127.
If
.Nm
encounters any other error, the exit status is between 1 and 125
included.
.Sh EXAMPLES
Time the execution of
.Xr ls 1
on an empty directory:
.Bd -literal -offset indent
$ /usr/bin/time ls
        0.00 real         0.00 user         0.00 sys
.Ed
.Pp
Time the execution of the
.Xr cp 1
command and store the result in the
.Pa times.txt
file.
Then execute the command again to make a new copy and add the result to the same
file:
.Bd -literal -offset indent
$ /usr/bin/time -o times.txt cp FreeBSD-12.1-RELEASE-amd64-bootonly.iso copy1.iso
$ /usr/bin/time -a -o times.txt cp FreeBSD-12.1-RELEASE-amd64-bootonly.iso copy2.iso
.Ed
.Pp
The
.Pa times.txt
file will contain the times of both commands:
.Bd -literal -offset indent
$ cat times.txt
        0.68 real         0.00 user         0.22 sys
        0.67 real         0.00 user         0.21 sys
.Ed
.Pp
Time the
.Xr sleep 1
command and show the results in a human friendly format.
Show the contents of the
.Em rusage
structure too:
.Bd -literal -offset indent
$ /usr/bin/time -l -h -p sleep 5
real 5.01
user 0.00
sys 0.00
         0  maximum resident set size
         0  average shared memory size
         0  average unshared data size
         0  average unshared stack size
        80  page reclaims
         0  page faults
         0  swaps
         1  block input operations
         0  block output operations
         0  messages sent
         0  messages received
         0  signals received
         3  voluntary context switches
         0  involuntary context switches
.Ed
.Sh SEE ALSO
.Xr builtin 1 ,
.Xr csh 1 ,
.Xr getrusage 2 ,
.Xr wait 2
.Sh STANDARDS
The
.Nm
utility is expected to conform to ISO/IEC 9945-2:1993 (``POSIX'').
.Sh HISTORY
A
.Nm
utility appeared in
.At v3 .