[20140627]time使用.txt

$ type -a time
time is a shell keyword
time is /usr/bin/time

--可以发现time有两个命令,1个是内置的,一个是外置的.

如果:

$ time  ls -l /etc/passwd
-rw-r--r--  1 root root 2874 2012-05-15 11:34:26 /etc/passwd

real    0m0.003s
user    0m0.001s
sys     0m0.002s

--如果要使用外部命令,可以使用:
$ /usr/bin/time -v ls -l /etc/passwd
-rw-r--r--  1 root root 2874 May 15  2012 /etc/passwd
        Command being timed: "ls -l /etc/passwd"
        User time (seconds): 0.00
        System time (seconds): 0.00
        Percent of CPU this job got: 50%
        Elapsed (wall clock) time (h:mm:ss or m:ss): 0:00.00
        Average shared text size (kbytes): 0
        Average unshared data size (kbytes): 0
        Average stack size (kbytes): 0
        Average total size (kbytes): 0
        Maximum resident set size (kbytes): 0
        Average resident set size (kbytes): 0
        Major (requiring I/O) page faults: 0
        Minor (reclaiming a frame) page faults: 252
        Voluntary context switches: 2
        Involuntary context switches: 1
        Swaps: 0
        File system inputs: 0
        File system outputs: 0
        Socket messages sent: 0
        Socket messages received: 0
        Signals delivered: 0
        Page size (bytes): 4096
        Exit status: 0

也可以使用如下:

\time -v ls -l /etc/passwd