Linux time command format

How to Time a Command in Linux

If you want to be a good Linux administrator, therefore you should know time command. It is used to determine how long a given command takes to run.

It is useful for testing the performance of your scripts and commands (ie helps to find execution time for shell scripts or time taken for a command to finish).

How to Use Linux time command

To use time command, just execute time with the command/program you want to run as input. Please check below example

The real signifies the wall clock time the ‘ping’ command took from execution till termination, user and sys are the time taken by ping the user space and kernel space.

How to Make time command writes its output to a file

To write the time command output to a file instead of the print out screen, use the -o command line option, which expects a file name/path as input.

Now we will display ping’s output on stdout, while the time command output will be written to the text file.

Note: We used /usr/bin/time instead of time because the shell built-in time command doesn’t offer the -o option.

How to appends its output to an existent file

To append the time command output to an existent file instead of overwrite it, use the -a command line option.

How to get Detailed output of linux time command

We can use the -v command line option to produce detailed output.

How to customizing time command output

There are a large number of formatting options as shown in the following list

C — Name and command line arguments used
D — Average size of the process’s unshared data area in kilobytes
E — Elapsed time in a clock format
F — Number of page faults
I — Number of file system inputs by the process
K — Average total memory use of the process in kilobytes
M — Maximum resident set the size of the process during the lifetime in Kilobytes
O — Number of file system outputs by the process
P — Percentage of CPU that the job received
R — Number of minor or recoverable page faults
S — Total number of CPU seconds used by the system in kernel mode
U — Total number of CPU seconds used by user mode
W — Number of times the process was swapped out of main memory
X — Average amount of shared text in the process
Z — System’s page size in kilobytes
c — Number of times the process was context-switched
e — Elapsed real 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 time the process was context-switched voluntarily
x — Exit status of the command

We can use the formatting switches as follows:

The output for the above command would be something like this:

If we want to add a new line as part of the format string use the newline character as follows:

Linux Time Command Versions

There are three-time command Versions, Bash, Zsh and Gnu time command. We can use the type command to determine whether time is a binary or a built-in keyword.

Please write your suggestions or comments on time command and for more information use time man pages.

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12 UNIX / Linux Time Command Output Format Option Examples

Linux time command is helpful to identify the time taken by a command.

Using Linux time command, you can figure out how much time was taken to execute a command, or shell script, or any other program.

By default, time command executes the given command or program. After execution, it displays the statistics and resources usage on the standard error.

Time command provides several command line options and various format options as explained in this tutorial

1. Basic Time Command Usage Example

Time command syntax:

For example, time command is run on sleep command without any option.

Let’s now understand some important command line options of this command.

2. Write Time Statistics Output to a File using -o option

This option is to restrict sending the command results to standard error, but writes results into output file. This option overwrites the specified file.

Here is an example :

3. Append Time Statistics Output to an Existing File using -a option

This option allows appending time command output into file. It is used along with -o option. This option avoids overwriting of content of output file by appending time command output into specified output file.

Here is an example :

4. Display Percentage of CPU used – %P

You can provide output formatting choices using -f option. This option allows user to provide output formatting options. It possibly does overriding the format specified in the environment variable TIME. Following formatting options are described below – %P, %M, %S, %e, %E, %C, %Z, %c, %x.

This option gives percentage of the CPU that the process of command (i.e. run under time command) has got for its execution. This is just user + system times divided by the total running time. It also prints a percentage sign.

Here, command output shows that find command took 82% of CPU.

5. Display Maximum Resident Set Size – %M

This option gives maximum resident set size of the process of command (i.e. run under time command) during its lifetime, in Kilobytes.

Here, command output shows that find command took 8688 KB as maximum resident size of process.

6. Display Total Number of CPU-seconds – %S

This option gives total number of CPU-seconds used by the system on behalf of the process (in kernel mode), in seconds.

Here, command output shows that find command took 0.35 CPU-seconds in kernel mode.

7. Display Elapsed Real Time in Seconds – %e

This option gives elapsed real time (i.e. wall clock) used by the process, in seconds.

Here, command output shows that sleep command execution elapsed till 2 seconds.

8. Display Elapsed Real Time in Different Format – %E

This option gives elapsed real time (i.e. wall clock) used by the process, in this format – [hours:]minutes:seconds.

Here, command output shows that sleep command execution took 0 hour, 0 minute and 2 seconds.

9. Display Program Name and Command Line Arguments – %C

This option gives name and command line arguments of the command (i.e. run under time command).

Here, time command output shows name of command being run and its command line arguments.

10. Display System Page Size in Bytes – %Z

This option gives system’s page size, in bytes. This is a per-system constant, but it may vary one system to another system.

Here, command output shows that sleep command used 4096 bytes as system page size.

11. Display Number of Context Switches – %c

This option gives number of times the process was context-switched involuntarily (because the time slice expired).

Here, command output shows that 254 times context switching of process took place during execution of find command under time command.

12. Display Exit Status of a Command – %x

This option gives exit status of the command (i.e. run under time command).

Here, command output shows that top1 command is failed because this tope1 as a file does not exist.

As per man page of time command, exit status of time command can be following:

• If command specified to time command was invoked, the exit status is the exit status of command which is run with time command.
• It is 127 if command specified to time command could not be found.
• 126 if command specified to time command could be found but could not be invoked.
• Some other non-zero value (1-125) if something else went wrong.

Finally, there is a difference between executing just “time” and “/usr/bin/time”. We explained this in our earlier introduction to time command article.

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How to use Linux time command

The time command is used to determine how long a given command takes to run. It is useful for testing the performance of your scripts and commands.
Good thing is time command comes preinstalled in most Linux distributions, so you don’t have to bother with installation.
In this article, we will discuss the basics of the time command using some easy to understand examples.

Using Linux Time Command

To use time command, just execute time with the command/program you want to run as input. Please check below example:

What will be printed as an output depends on the version of the time command you’re using:

• real or total or elapsed (wall clock time) is the time from start to finish of the call. It is the time from the moment you hit the Enter key until the moment the wget command is completed.
• user – amount of CPU time spent in user mode.
• system or sys – amount of CPU time spent in kernel mode.

How to Make time command writes its output to a file

To write the time command output to a file instead of the print out screen, use the -o command line option, which expects a file name/path as input.

Now we will display wget output on stdout, while the time command output will be written to the text file.

How to make time produce detailed output

We can use the -v command line option to produce detailed output.

How to customizing time command output

There are a large number of formatting options as shown in the following list:

C – Name and command line arguments used
D – Average size of the process’s unshared data area in kilobytes
E – Elapsed time in a clock format
F – Number of page faults
I – Number of file system inputs by the process
K – Average total memory use of the process in kilobytes
M – Maximum resident set the size of the process during the lifetime in Kilobytes
O – Number of file system outputs by the process
P – Percentage of CPU that the job received
R – Number of minor or recoverable page faults
S – Total number of CPU seconds used by the system in kernel mode
U – Total number of CPU seconds used by user mode
W – Number of times the process was swapped out of main memory
X – Average amount of shared text in the process
Z – System’s page size in kilobytes
c – Number of times the process was context-switched
e – Elapsed real 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 time the process was context-switched voluntarily
x – Exit status of the command

We can use the formatting switches as follows:

produced this output:

Linux Time Command Versions

There are three-time command Versions, Bash, Zsh and Gnu time command. We can use the type command to determine whether time is a binary or a built-in keyword.

The time command man page contains details related to the format command line option.

Conclusion

The time command is mostly used by software developers and testers. More info about this command can be accessed through the tool’s man page. In case if you find this article informative then please do share your feedback and comments.

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Команда time в Linux

Команда time используется для определения того, сколько времени требуется для выполнения данной команды. Это полезно для тестирования производительности ваших скриптов и команд.

Например, если у вас есть два разных сценария, выполняющих одну и ту же работу, и вы хотите знать, какой из них работает лучше, вы можете использовать команду Linux time, чтобы определить продолжительность выполнения каждого сценария.

Версии Time Command

Как Bash, так и Zsh, наиболее широко используемые оболочки Linux, имеют свои собственные встроенные версии команды time, которые имеют приоритет над командой времени Gnu.

Вы можете использовать команду type чтобы определить, является ли время двоичным или встроенным ключевым словом.

Чтобы использовать команду Gnu time, вам необходимо указать полный путь к двоичному файлу времени, обычно /usr/bin/time , использовать команду env или использовать начальную обратную косую черту time которая предотвращает использование обоих и встроенных модулей.

Gnu time позволяет форматировать вывод и предоставляет другую полезную информацию, такую как ввод-вывод памяти и вызовы IPC.

Использование команды времени Linux

В следующем примере мы собираемся измерить время, необходимое для загрузки ядра Linux с помощью инструмента wget :

То, что будет напечатано в качестве вывода, зависит от версии используемой вами команды time:

• реальное или общее или прошедшее (время настенных часов) — это время от начала до конца разговора. Это время с момента нажатия клавиши Enter до момента завершения команды wget .
• user — количество процессорного времени, проведенного в пользовательском режиме.
• system или sys — количество процессорного времени, потраченного в режиме ядра.

Выводы

К настоящему времени вы должны хорошо понимать, как использовать команду времени. Если вы хотите узнать больше о команде Gnu time, посетите страницу руководства time .

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How To Format Date For Display or Use In a Shell Script

H ow do I format the date to display on the screen on for my shell scripts as per my requirements on Linux or Unix like operating systems?

You need to use the standard date command to format date or time in Linux or Unix shell scripts. You can use the same command with the shell script. This page shows how to format date in Linux or Unix-based system.

Tutorial details
Difficulty level	Easy
Root privileges	No
Requirements	date on Linux/Unix
Est. reading time	7 minutes

Linux Syntax To Format Date For Display On Screen

The syntax is as follows for the GNU/date and BSD/date command:
date +FORMAT
date +»%FORMAT»
date +»%FORMAT%FORMAT»
date +»%FORMAT-%FORMAT»
An operand with a leading plus ( + ) sign signals a user-defined format string which specifies the format in which to display the date and time. The following examples are tested on GNU/Linux, Apple OS X Unix, and FreeBSD unix operating system.

Task: Display date in mm-dd-yy format

Open a terminal and type the following date command:
$ date +»%m-%d-%y»
Sample outputs:

To turn on 4 digit year display:
$ date +»%m-%d-%Y»
Just display date as mm/dd/yy format:
$ date +»%D»

Task: Display time only

Type the following command:
$ date +»%T»
Sample outputs:

To display locale’s 12-hour clock time, enter:
$ date +»%r»
Sample outputs:

To display time in HH:MM format, type:
$ date +»%H-%M»
Sample outputs:

How do I save time/date format to the shell variable?

Simply type the following command at the shell prompt to get the current date in MM-DD-YYYY format:
$ NOW=$(date +»%m-%d-%Y»)
To display a variable use the following simple commands to output on screen under Linux and UNIX using the printf command/echo command:
$ echo «$NOW»
printf «%s\n» $NOW

A sample shell script

A complete list of FORMAT control characters supported by the GNU/date command

It can be the combination of any one of the following:

Table 1 – FORMAT controls the output for Linux

%FORMAT String	Description
%%	a literal %
%a	locale’s abbreviated weekday name (e.g., Sun)
%A	locale’s full weekday name (e.g., Sunday)
%b	locale’s abbreviated month name (e.g., Jan)
%B	locale’s full month name (e.g., January)
%c	locale’s date and time (e.g., Thu Mar 3 23:05:25 2005)
%C	century; like %Y, except omit last two digits (e.g., 21)
%d	day of month (e.g, 01)
%D	date; same as %m/%d/%y
%e	day of month, space padded; same as %_d
%F	full date; same as %Y-%m-%d
%g	last two digits of year of ISO week number (see %G)
%G	year of ISO week number (see %V); normally useful only with %V
%h	same as %b
%H	hour (00..23)
%I	hour (01..12)
%j	day of year (001..366)
%k	hour ( 0..23)
%l	hour ( 1..12)
%m	month (01..12)
%M	minute (00..59)
%n	a newline
%N	nanoseconds (000000000..999999999)
%p	locale’s equivalent of either AM or PM; blank if not known
%P	like %p, but lower case
%r	locale’s 12-hour clock time (e.g., 11:11:04 PM)
%R	24-hour hour and minute; same as %H:%M
%s	seconds since 1970-01-01 00:00:00 UTC
%S	second (00..60)
%t	a tab
%T	time; same as %H:%M:%S
%u	day of week (1..7); 1 is Monday
%U	week number of year, with Sunday as first day of week (00..53)
%V	ISO week number, with Monday as first day of week (01..53)
%w	day of week (0..6); 0 is Sunday
%W	week number of year, with Monday as first day of week (00..53)
%x	locale’s date representation (e.g., 12/31/99)
%X	locale’s time representation (e.g., 23:13:48)
%y	last two digits of year (00..99)
%Y	year
%z	+hhmm numeric timezone (e.g., -0400)
%:z	+hh:mm numeric timezone (e.g., -04:00)
%::z	+hh:mm:ss numeric time zone (e.g., -04:00:00)
%. z	numeric time zone with : to necessary precision (e.g., -04, +05:30)
%Z	alphabetic time zone abbreviation (e.g., EDT)

A complete list of FORMAT control characters supported by the BSD/date command

The following works on Apple macOS/OS X, FreeBSD and *BSD version of the date command:

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Table 2 – BSD/date command

%FORMAT String	Description
%A	is replaced by national representation of the full weekday name.
%a	is replaced by national representation of the abbreviated weekday name.
%B	is replaced by national representation of the full month name.
%b	is replaced by national representation of the abbreviated month name.
%C	is replaced by (year / 100) as decimal number; single digits are preceded by a zero.
%c	is replaced by national representation of time and date.
%D	is equivalent to “%m/%d/%y”.
%d	is replaced by the day of the month as a decimal number (01-31).
%E* %O*	POSIX locale extensions. The sequences %Ec %EC %Ex %EX %Ey %EY %Od %Oe %OH %OI %Om %OM %OS %Ou %OU %OV %Ow %OW %Oy are supposed to provide alternate representations. Additionally %OB implemented to represent alternative months names (used standalone, without day mentioned).
%e	is replaced by the day of the month as a decimal number (1-31); single digits are preceded by a blank.
%G	is replaced by a year as a decimal number with century. This year is the one that contains the greater part of the week (Monday as the first day of the week).
%g	is replaced by the same year as in “%G”, but as a decimal number without century (00-99).
%H	is replaced by the hour (24-hour clock) as a decimal number (00-23).
%h	the same as %b.
%I	is replaced by the hour (12-hour clock) as a decimal number (01-12).
%j	is replaced by the day of the year as a decimal number (001-366).
%k	is replaced by the hour (24-hour clock) as a decimal number (0-23); single digits are preceded by a blank.
%l	is replaced by the hour (12-hour clock) as a decimal number (1-12); single digits are preceded by a blank.
%M	is replaced by the minute as a decimal number (00-59).
%m	is replaced by the month as a decimal number (01-12).
%n	is replaced by a newline.
%O*	the same as %E*.
%p	is replaced by national representation of either “ante meridiem” (a.m.) or “post meridiem” (p.m.) as appropriate.
%R	is equivalent to “%H:%M”.
%r	is equivalent to “%I:%M:%S %p”.
%S	is replaced by the second as a decimal number (00-60).
%s	is replaced by the number of seconds since the Epoch, UTC (see mktime(3)).
%T	is equivalent to “%H:%M:%S”.
%t	is replaced by a tab.
%U	is replaced by the week number of the year (Sunday as the first day of the week) as a decimal number (00-53).
%u	is replaced by the weekday (Monday as the first day of the week) as a decimal number (1-7).
%V	is replaced by the week number of the year (Monday as the first day of the week) as a decimal number (01-53). If the week containing January 1 has four or more days in the new year, then it is week 1; otherwise it is the last week of the previous year, and the next week is week 1.
%v	is equivalent to “%e-%b-%Y”.
%W	is replaced by the week number of the year (Monday as the first day of the week) as a decimal number (00-53).
%w	is replaced by the weekday (Sunday as the first day of the week) as a decimal number (0-6).
%X	is replaced by national representation of the time.
%x	is replaced by national representation of the date.
%Y	is replaced by the year with century as a decimal number.
%y	is replaced by the year without century as a decimal number (00-99).
%Z	is replaced by the time zone name.
%z	is replaced by the time zone offset from UTC; a leading plus sign stands for east of UTC, a minus sign for west of UTC, hours and minutes follow with two digits each and no delimiter between them (common form for RFC 822 date headers).
%+	is replaced by national representation of the date and time (the format is similar to that produced by date(1)).
%-*	GNU libc extension. Do not do any padding when performing numerical outputs.
%_*	GNU libc extension. Explicitly specify space for padding.
%0*	GNU libc extension. Explicitly specify zero for padding.
%%	is replaced by %.

A sample date session

I am running commands on macOS/OS X and FreeBSD:

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