`time` is a command line utility for running another program and summarizing resource usage

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36
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Timezone setting in Linux [closed]

I'm setting the timezone to GMT+6 on my Linux machine by copying the zoneinfo file to /etc/localtime, but the date command is still showing the time as UTCtime-6. Can any one explain to me this ...
32
votes
6answers
75k views

How to measure time of program execution and store that inside a variable

In order to find out how long certain operations within a Bash (v4+) script take, I would like to parse the output from the time command "separately" and (ultimately) capture it within a Bash variable ...
30
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3answers
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Why does Unix time start at 1970-01-01?

Why does Unix time start at 1970-01-01? Why not 1971-01-01 or any other date?
27
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1answer
2k views

Why does “ls *” take so much longer than “ls”?

I have a couple of files in a directory: $ ls | wc -l 9376 Can anybody explain why there is such a huge time difference in using ls * and ls? $ time ls > /dev/null real 0m0.118s user ...
27
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1answer
1k views

Why does echo >file use more real time than echo | sed >file?

The example, below, surprised me. It seems to be counter intuitive... aside from the fact that there is a whisker more user time for the echo | sed combo. Why is echo using so much sys time when it ...
26
votes
2answers
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What units of time does “top” use?

If I issue the "top" command and receive results such as: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 00001 bob 25 0 77380 1212 1200 R 95.8 0.0 89122:13 fee ...
24
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1answer
6k views

Run a command for a specified time and then abort if time exceeds

I want know how I can run a command for a specified time say, one minute and if it doesn't complete execution then I should be able to stop it.
16
votes
2answers
897 views

Is there something like `time` that also records I/O and CPU?

I can pretty quickly monitor the running time of a process with time: x@y ~ $ time foo real 0m14.299s user 0m4.770s sys 0m0.440s Is there a way I can get the same data for ...
14
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8answers
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How to check if NTPD updates machine's time successfully using shell?

I'm trying to use NTPD to update my Linux machine's time to a specified NTP server. Here is the scenario: Each time the Linux machine starts up, I want to update the time from NTP server and if ...
13
votes
4answers
7k views

Why is scp so slow and how to make it faster?

I'm trying to copy a batch of files with scp but it is very slow. This is an example with 10 files: $ time scp cap_* user@host:~/dir cap_20151023T113018_704979707.png 100% 413KB 413.2KB/s 00:00 ...
13
votes
1answer
3k views

Why would the “real” time be much higher than the “user” and “sys” times combined?

I execute and time many commands (i.e. nslookup) through SSH and I collect the total time needed for the implied service to complete (i.e. DNS). So I collect the user and sys time as the real time ...
13
votes
3answers
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What is the recommended way to synchronize time using NTP?

This question has come up a number of times in a localized way, this question is meant to provide the preferred/best method for synchronizing a system's clock using NTP. The solution should handle ...
12
votes
3answers
2k views

How to average time commands?

I am timeing some of my commands. Now to average the measures, I'd like to run and time my commands a specified number of times, and get the results with a calculated mean and standard deviation. The ...
10
votes
4answers
2k views

How can measure how long it takes my script to run AND include that in an email it generates?

I have a simple bash script that runs a series of checks (ping, nslookup, etc) and then sends an email report with the output of that data. I'd like the email to include information on how long it ...
10
votes
2answers
7k views

Why real time can be lower than user time

I have a script converting video files and I run it at server on test data and measure its time by time. In result I saw: real 2m48.326s user 6m57.498s sys 0m3.120s Why real time is that ...
10
votes
1answer
6k views

Increase %e precision with /usr/bin/time shell command

When I run the time command in shell time ./myapp I get an output like the following: real 0m0.668s user 0m0.112s sys 0m0.028s However,when I run the command \time -f %e ./myapp I lose ...
10
votes
3answers
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Why is my EC2 server's time off by ~10 seconds every day?

I have what I believe is a system file, /etc/cron.daily/ntpupdate which runs ntpdate ntp.ubuntu.com daily to sync with the network time. Every day it generates output very similar to this: ...
10
votes
1answer
2k views

Measuring disk I/O usage of a program

time is a brilliant command if you want to figure out how much CPU time a given command takes. I am looking for something similar that can measure the disk I/O of the program and any children. ...
9
votes
2answers
2k views

Temporarily change time

I need to test aspects of my software that only happen at certain times of the day. Rather than waiting whole days (and getting here at 2:00 AM), I'd like to change the time. But I'd rather not ...
9
votes
2answers
250 views

How can I conditionally pass a subshell through 'time'?

I have a setup script for a Vagrant box where I used to measure single steps with time. Now I would like to conditionally enable or disable the time measurements. For example, previously a line would ...
9
votes
2answers
3k views

How to get the time of several commands with a loop

I have this command: time -p sh -c 'command1; command2;' So command1and command2 is executed and I get the real, user and sys time printed on the console. But I want that command1; command2; is ...
9
votes
4answers
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Forcing an 'added' alias to every command

Is it possible to forcibly add a timing alias (for lack of a better way to phrase it) to every command in bash? For example, I would like to have a specific user who whenever a command is run, it is ...
9
votes
2answers
4k views

Is there a way to adjust the formatting of the date/time in the GNOME 3 login screen and desktop?

I'm specifically looking to change the formatting in two places: On the desktop, the date/time reads "Sat 21:05". I would like it to read "23-Jul-11 21:05" or "23 Jul 11 21:05". In other words, I ...
8
votes
3answers
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Measuring time within a script

This thread shows how to measure the time it takes to run a script. In my case, I am interested in measuring time between two points within a script. Here is an example of how I would like to use ...
8
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1answer
1k views

Why bash time is more precise then GNU time?

The buitin bash command time gives milisecond precision of execution and GNU time (usually /usr/bin/time) gives centisecond precision. The times(2) syscall gives times in clocks, and 100 clocks = 1 ...
7
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5answers
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Convert linux sysuptime to well format date

I want to display /proc/uptime in well format as: DD:HH:MM:SS /proc/uptime give me up time of system in seconds, is there a standard solution that convert seconds to this format?
7
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2answers
353 views

How can other processes affect measurements made with `time`?

If I time a process using the time command, I get output for 'real', 'user', and 'sys'. My understanding from this discussion is that 'real' is wall time, whereas 'user' and 'sys' are process time. ...
7
votes
2answers
2k views

Memory usage command with syntax similar to the time command

What command shows the memory usage of a program, i am looking for a command that is simple to use and has similar syntax to the time command. I am trying to find the memory usage of a md5 hashing ...
7
votes
2answers
1k views

How can I get the wall clock time of a running process?

I started a hash check of a large file and don't want to restart it using time. How can I get the wall clock time without using time at the beginning or using date right before I invoke a command?
7
votes
2answers
16k views

Good method to compare time?

I need to check for the current time and abort the script if it is not proper time of day I am supposed to run it. Also, if anyone else runs it, it should abort. For example: I need my script to only ...
7
votes
1answer
203 views

NTP and NTPD Nanokernel

I had a couple of questions about the NTP Nanokernel as explained here: http://www.eecis.udel.edu/~mills/database/brief/nano/nano.pdf The big question is how does this Nanokernel manage to deliver an ...
7
votes
1answer
120 views

Time all executions in bash [duplicate]

Is there a way to run all commands in bash as if they were invoked with time in front? I want that I could type $ some_command and this will actually invoke $ time some_command.
6
votes
3answers
4k views

Sleep until next occurrence of specific time

I need a series of commands or a single command that sleeps until the next occurrence of a specific time like "4:00" occurs. How would I do that? The at command or a cronjob is not a option because ...
6
votes
1answer
2k views

bash time with nohup

I want to know how much time it takes to run something in nohup. I know this works: $ time sleep 2 real 0m2.001s user 0m0.000s sys 0m0.001s But why it doesn't work with nohup? $ nohup ...
6
votes
1answer
50 views

GNU find -[cma]time option and daylight saving time

In the GNU find man, you can read this about the -atime option: -atime n File was last accessed n*24 hours ago. When find figures out how many 24-hour periods ago the file was last ...
6
votes
1answer
903 views

stat: print time in “long-iso” format

For my script, I would like to have stat command to print time in a nice, human friendly, way: 2015-02-04 00:48:31. ls calls this format long-iso and it can be used like this: $ ls -lA ...
5
votes
5answers
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How to get system time with microsecond Resolution

I want to know current system time with microsecond Resolution. date +%s returns Time in seconds since epoch(1-1-1970). How can I get time in microseconds Resolution. How much delay is in querying ...
5
votes
3answers
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Disable daylight saving time in Debian Linux

I do not want my system to use daylight saving time. root@ali-debserver:~# cat /etc/timezone Asia/Tehran root@ali-debserver:~# cat /etc/default/rcS # # /etc/default/rcS # # Default settings for the ...
5
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2answers
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how does time command work

So when I type time <some_program> I have nice CPU time measurement. But exactly how is this achieved? Also does this have any performance impact on the some_program?
5
votes
1answer
744 views

when timing a command execution time with sudo, `time` should be before `sudo` or after `sudo`?

when timing a command execution time with sudo, time should be before sudo or after sudo? time sudo command or sudo time command which one is correct? the output seems very different to me ...
5
votes
3answers
403 views

Unix epoch in milliseconds

I'm prepending the Unix epoch with "nanosecond" precision into output of my command as below: $ command | while read line; do d=`date +%s%N`; echo $d $line; done > file I looked around to find ...
5
votes
3answers
2k views

How can I profile a shell script?

I have several programs that i'm executing in a shell script: ./myprogram1 ./myprogram2 ... I know that I can profile each individual program by editing the sourcecode, but I wanted to know if ...
5
votes
3answers
435 views

How to measure Firefox's startup time?

I would like to measure how much time it takes for some softwares to start. I know the command time but in the case of firefox (iceweasel for me on Debian), this command prints only the time I let ...
5
votes
1answer
10k views

Understanding ps elapsed time format for long running processes

I'm using a ps command as part of an exercise to identify processes running longer than a given threshold. I'm using the following template to get the elapsed time for a know process command: ps -eo ...
5
votes
2answers
222 views

NTP tool for showing deviance to a certain server

I am searching for a command-line that allows me to check the system time deviance to a NTP server specified on the command-line. I don't want to change/adapt the system time - only displays the ...
5
votes
2answers
561 views

How to control the time that users spend on

I need a solution that allows me to control the time that each user spend on the computer, excluding idle time (some kind of parental control). I've tried timekpr, but it doesn't work on Ubuntu 13.10. ...
5
votes
2answers
260 views

How to report time and other information on all bash commands? [duplicate]

Most of the things I run in the terminal take a long time to compute and I would like to have bash output a time report at the end of every command entered into the terminal. Is there something I can ...
5
votes
1answer
216 views

linux patches related to time measurement accuracy?

Is there a set of patches around for linux kernel that address accuracy of (system, rather than user) process time? i've heard about RTLinux, but i don't really need the actual real-time scheduling ...
4
votes
4answers
655 views

Can I write the output the of time difference command to a file?

Can I write the output of the time difference command to a file? For example, I tried: $ time foo.sh > bar.txt But it only gives the output of foo.sh to bar.txt.
4
votes
1answer
286 views

CPU is free, yet bash script not utilizing all CPU resources

I ran a simple script to generate a large (10000000 lines) csv file with 6 fields in which some fields changed in each line/row, using a while loop. The machine had all (32) CPUs free, lot of RAM (~31 ...