yuyabuThere are two types of time commands.
- bash built-in time command
- gnu time
The gnu time command can measure cpu usage, average memory usage, maximum memory usage, etc.
Although the default output format is hard to see, users can define their own format and select only the necessary information.
Environmental information
$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=18.04
DISTRIB_CODENAME=bionic
DISTRIB_DESCRIPTION="Ubuntu 18.04.2 LTS"
FORMATTING THE OUTPUT
| % | A literal `%'. |
|----|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| C | Name and command line arguments of the command being timed. |
| D | Average size of the process's unshared data area, in Kilobytes. |
| E | Elapsed real (wall clock) time used by the process, in [hours:]minutes:seconds. |
| F | Number of major, or I/O-requiring, page faults that occurred while the process was running. These are faults where the page has actually migrated out of primary memory. |
| I | Number of file system inputs by the process. |
| K | Average total (data+stack+text) memory use of the process, in Kilobytes. |
| M | Maximum resident set size of the process during its lifetime, in Kilobytes. |
| O | Number of file system outputs by the process. |
| P | Percentage of the CPU that this job got. This is just user + system times divided by the total running time. It also prints a percentage sign. |
| R | Number of minor, or recoverable, page faults. These are pages that are not valid (so they fault) 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. |
| S | Total number of CPU-seconds used by the system on behalf of the process (in kernel mode), in seconds. |
| U | Total number of CPU-seconds that the process used directly (in user mode), in seconds. |
| W | Number of times the process was swapped out of main memory. |
| X | Average amount of shared text in the process, in Kilobytes. |
| Z | System's page size, in bytes. This is a per-system constant, but varies between systems. |
| c | Number of times the process was context-switched involuntarily (because the time slice expired). |
| e | Elapsed real (wall clock) time used by the process, in seconds. |
| k | Number of signals delivered to the process. |
| p | Average unshared stack size of the process, in Kilobytes. |
| r | Number of socket messages received by the process. |
| s | Number of socket messages sent by the process. |
| t | Average resident set size of the process, in Kilobytes. |
| w | Number of times that the program was context-switched voluntarily, for instance while waiting for an I/O operation to complete. |
| x | Exit status of the command.
(this table from manpage of time)
You can register the format in the environment variable $ TIME or specify the format with -f option.
export TIME="time result\ncmd:%C\nreal %es\nuser %Us \nsys %Ss \nmemory:%MKB \ncpu %P"
or
time -f "time result\ncmd:%C\nreal %es\nuser %Us \nsys %Ss \nmemory:%MKB \ncpu %P" <command>
Execution result (running and check sleep command)
$ /usr/bin/time sleep 1
time result
cmd:sleep 1
real 1.00s
user 0.00s
sys 0.00s
memory:2128KB
cpu 0%
