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

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.\"     @(#)time.1	8.1 (Berkeley) 6/6/93
.\"     $Id$
.\"
.Dd June 6, 1993
.Dt TIME 1
.Os BSD 4
.Sh NAME
.Nm time
.Nd time command execution
.Sh SYNOPSIS
.Nm
.Op Fl alp
.Op Fl o Ar file
.Ar command
.Sh DESCRIPTION
The
.Nm
utility
executes and
times
.Ar command
by initiating a timer and passing the
.Ar command
to the
shell.
After the
.Ar command
finishes,
.Nm
writes to the standard error stream,
(in seconds): 
the total time elapsed,
the time used to execute the
.Ar command
process and the time consumed by system overhead.
.Pp
Available options:
.Bl -tag -width Ds
.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 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
Most shells (including
.Xr csh 1 )
have their own and syntactically different builtin version of
.Nm time .
The command described here
is available as
.Pa /usr/bin/time
to users of those shells.
.Sh DIAGNOSTICS
If
.Ar command
could be timed successfully, its exit status is returned. In case
.Ar command
terminated abnormally, a warning message is output to stderr.
If the 
.Ar command
was found but could not be run, the exit status is 126.
If no
.Ar command
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 SEE ALSO
.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
command appeared in
.At v6 .