| ranger_nemo |
08-18-2004 09:24 PM |
Code:
TIME(1) TIME(1)
NAME
time - time a simple command or give resource usage
SYNOPSIS
time[options] command [arguments...]
DESCRIPTION
The time command runs the specified program command with
the given arguments. When command finishes, time writes a
message to standard output giving timing statistics about
this program run. These statistics consist of (i) the
elapsed real time between invocation and termination, (ii)
the user CPU time (the sum of the tms_utime and tms_cutime
values in a struct tms as returned by times(2)), and (iii)
the system CPU time (the sum of the tms_stime and
tms_cstime values in a struct tms as returned by
times(2)).
OPTION
-p When in the POSIX locale, use the precise tradi_
tional format
"real %f\nuser %f\nsys %f\n"
(with numbers in seconds) where the number of deci_
mals in the output for %f is unspecified but is
sufficient to express the clock tick accuracy, and
at least one.
ENVIRONMENT
The variables LANG, LC_ALL, LC_CTYPE, LC_MESSAGES,
LC_NUMERIC, NLSPATH and PATH are used. The last one to
search for command. The remaining ones for the text and
formatting of the output.
EXITSTATUS
If command was invoked, the exit status is that of com_
mand. Otherwise it is 127 if command could not be found,
126 if it could be found but could not be invoked, and
some other nonzero value (1-125) if something else went
wrong.
SEEALSO
times(2),
GNUVERSION
Below a description of the GNU 1.7 version of time. Dis_
regarding the name of the utility, GNU makes it output
lots of useful information, not only about time used, but
also on other resources like memory, I/O and IPC calls
(where available). The output is formatted using a format
string that can be specified using the -f option or the
TIME environment variable.
The default format string is
%Uuser %Ssystem %Eelapsed %PCPU (%Xtext+%Ddata %Mmax)k
%Iinputs+%Ooutputs (%Fmajor+%Rminor)pagefaults %Wswaps
When the -p option is given the (portable) output format
real %e
user %U
sys %S
is used.
Theformatstring
The format is interpreted in the usual printf-like way.
Ordinary characters are directly copied, tab, newline and
backslash are escaped using \t, \n and \\, a percent sign
is represented by %%, and otherwise % indicates a conver_
sion. The program time will always add a trailing newline
itself. The conversions follow. All of those used by
tcsh(1) are supported.
Time
%E Elapsed real time (in [hours:]minutes:seconds).
%e (Not in tcsh.) Elapsed real time (in seconds).
%S Total number of CPU-seconds that the process spent
in kernel mode.
%U Total number of CPU-seconds that the process spent
in user mode.
%P Percentage of the CPU that this job got, computed
as (%U + %S) / %E.
Memory
%M Maximum resident set size of the process during its
lifetime, in Kbytes.
%t (Not in tcsh.) Average resident set size of the
process, in Kbytes.
%K Average total (data+stack+text) memory use of the
process, in Kbytes.
%D Average size of the process's unshared data area,
in Kbytes.
%p (Not in tcsh.) Average size of the process's
unshared stack space, in Kbytes.
%X Average size of the process's shared text space, in
Kbytes.
%Z (Not in tcsh.) System's page size, in bytes. This
is a per-system constant, but varies between sys_
tems.
%F Number of major page faults that occurred while the
process was running. These are faults where the
page has to be read in from disk.
%R Number of minor, or recoverable, page faults.
These are faults for pages that are not valid but
which have not yet been claimed by other virtual
pages. Thus the data in the page is still valid
but the system tables must be updated.
%W Number of times the process was swapped out of main
memory.
%c Number of times the process was context-switched
involuntarily (because the time slice expired).
%w Number of waits: times that the program was con_
text-switched voluntarily, for instance while wait_
ing for an I/O operation to complete.
I/O
%I Number of file system inputs by the process.
%O Number of file system outputs by the process.
%r Number of socket messages received by the process.
%s Number of socket messages sent by the process.
%k Number of signals delivered to the process.
%C (Not in tcsh.) Name and command line arguments of
the command being timed.
%x (Not in tcsh.) Exit status of the command.
GNUOPTIONS
-f FORMAT,--format=FORMAT
Specify output format, possibly overriding the for_
mat specified in the environment variable TIME.
-p,--portability
Use the portable output format.
-o FILE,--output=FILE
Do not send the results to stderr, but overwrite
the specified file.
-a,--append
(Used together with -o.) Do not overwrite but
append.
-v,--verbose
Give very verbose output about all the program
knows about.
GNUSTANDARDOPTIONS
--help Print a usage message on standard output and exit
successfully.
-V,--version
Print version information on standard output, then
exit successfully.
-- Terminate option list.
BUGS
Not all resources are measured by all versions of Unix, so
some of the values might be reported as zero. The present
selection was mostly inspired by the data provided by 4.2
or 4.3BSD.
GNU time version 1.7 is not yet localized. Thus, it does
not implement the POSIX requirements.
The environment variable TIME was badly chosen. It is not
unusual for systems like autoconf or make to use environ_
ment variables with the name of a utility to override the
utility to be used. Uses like MORE or TIME for options to
programs (instead of program path names) tend to lead to
difficulties.
It seems unfortunate that -o overwrites instead of
appends. (That is, the -a option should be the default.)
Mail suggestions and bug reports for GNU time to
bug-utilsprep.edu
Please include the version of time, which you can get by
running
time --version
and the operating system and C compiler you used.
SEEALSO
tcsh(1), times(2), wait3(2)
AUTHORS
David Keppel
Original version
David MacKenzie
POSIXization, autoconfiscation, GNU getopti_
zation, documentation, other bug fixes and
improvements.
Arne Henrik Juul
Helped with portability
Francois Pinard
Helped with portability
2000-12-11 TIME(1)
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