TIME(1)

NAME
time - time command execution

SYNOPSIS
time [-al] [-h | -p] [-o file] utility [argument ...]

DESCRIPTION
The time utility executes and times the specified utility. After the utility finishes, time writes to the standard error stream, (in seconds): the total time elapsed, the time used to execute the utility process and the time consumed by system overhead.

The following options are available:

-a  If the -o flag is used, append to the specified file rather than overwriting it. Otherwise, this option has no effect.

-h  Print times in a human friendly format. Times are printed in minutes, hours, etc. as appropriate.

-l  The contents of the rusage structure are printed as well.

-o file
    Write the output to file instead of stderr. If file exists and the -a flag is not specified, the file will be overwritten.

-p  Makes time output POSIX.2 compliant (each time is printed on its own line).

Some shells may provide a builtin time command which is similar or identical to this utility. Consult the builtin(1) manual page.

If time receives a SIGINFO (see the status argument for stty(1)) signal, the current time the given command is running will be written to the standard output.

ENVIRONMENT
The PATH environment variable is used to locate the requested utility if the name contains no ‘/’ characters.

EXIT STATUS
If utility could be timed successfully, its exit status is returned. If the utility was found but could not be run, the exit status is 126. If no utility could be found at all, the exit status is 127. If time encounters any other error, the exit status is between 1 and 125 included.

DIAGNOSTICS
If utility terminated abnormally, a warning message is output to stderr.

SEE ALSO
builtin(1), csh(1), getrusage(2), wait(2)

STANDARDS
The time utility is expected to conform to ISO/IEC 9945-2:1993 (``POSIX'').

HISTORY
A time utility appeared in AT&T UNIX.