TIME(1) — UNIX Programmer’s Manual

NAME

time − time a command

SYNOPSIS

time command

DESCRIPTION

The given command is executed; after it is complete, time prints the elapsed (real) time during the command, the time spent in the system, and the time spent in execution of the command.

Times are reported in seconds. The times are printed on the diagnostic output stream.

Time is also built in to csh(1), but it uses a different output format.

EXAMPLE

time nroff man filea

will, in sh, perform the formatting and report the time at the end of the file, e.g.:

real 22.0
user 8.6
sys 6.4

In csh, on the other hand, the time report might be:

8.9u 7.0s 0:29 54%

which reports the user time, system time, real time, and percentage of real time that the CPU was active, which is the sum of the user and system times divided by real elapsed time.

BUGS

Elapsed time is accurate to the second, while the CPU times are measured to the 60th second. Thus the sum of the CPU times can be up to a second larger than the elapsed time.