NAME
time
—
time command execution
SYNOPSIS
time |
[-clp ] [-f
fmt] command
[argument ...] |
DESCRIPTION
Thetime
utility executes and times
command. After the command finishes,
time
writes the total elapsed time (wall clock time),
(“real”), the CPU time spent executing
command at user level (“user”), and the
CPU time spent executing in the operating system kernel (“sys”),
to the standard error stream. Times are reported in seconds.
Available options:
-c
- Displays information in the format used by default the
time
builtin of csh(1) uses (%Uu %Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww). -f
- Specify a time format using the
csh(1)
time
builtin syntax. The following sequences may be used in the format string:- %U
- The time the process spent in user mode in cpu seconds.
- %S
- The time the process spent in kernel mode in cpu seconds.
- %E
- The elapsed (wall clock) time in seconds.
- %P
- The CPU percentage computed as (%U + %S) / %E.
- %W
- Number of times the process was swapped.
- %X
- The average amount in (shared) text space used in Kbytes.
- %D
- The average amount in (unshared) data/stack space used in Kbytes.
- %K
- The total space used (%X + %D) in Kbytes.
- %M
- The maximum memory the process had in use at any time in Kbytes.
- %F
- The number of major page faults (page needed to be brought from disk).
- %R
- The number of minor page faults.
- %I
- The number of input operations.
- %O
- The number of output operations.
- %r
- The number of socket messages received.
- %s
- The number of socket messages sent.
- %k
- The number of signals received.
- %w
- The number of voluntary context switches (waits).
- %c
- The number of involuntary context switches.
-l
- Lists resource utilization information. The contents of the command process's rusage structure are printed; see below.
-p
- The output is formatted as specified by IEEE Std 1003.2-1992 (“POSIX.2”).
-t
- Displays information in the format used by default the
time
builtin of tcsh(1) uses (%Uu %Ss %E %P\t%X+%Dk %I+%Oio %Fpf+%Ww) with three decimal places for time values.
Some shells, such as
csh(1) and ksh(1), have their own and syntactically different built-in
version of time
. The utility described here is
available as /usr/bin/time to users of these
shells.
Resource Utilization
If the -l
option is given, the following
resource usage information is displayed in addition to the timing
information:
- maximum resident set size
- average shared memory size
- average unshared data size
- average unshared stack size
- page reclaims
- page faults
- swaps
- block input operations
- block output operations
- messages sent
- messages received
- signals received
- voluntary context switches
- involuntary context switches
FILES
- ⟨sys/resource.h⟩
EXIT STATUS
The time
utility exits with one of the
following values:
- 1-125
- An error occurred in the
time
utility. - 126
- The command was found but could not be invoked.
- 127
- The command could not be found.
Otherwise, the exit status of time
will be
that of command.
SEE ALSO
STANDARDS
The time
utility conforms to
IEEE Std 1003.2-1992 (“POSIX.2”).
BUGS
The granularity of seconds on microprocessors is crude and can result in times being reported for CPU usage which are too large by a second.