Custom format for time command

Question

I d like to use the time command in a bash script to calculate the elapsed time of the script and write that to a log file   I only need the real time  not the user and sys   Also need it in a decent format  e g 00 00 00 00  not like the standard output    I appreciate any advice   The expected format supposed to be 00 00 00 0000  milliseconds   hours   minutes   seconds   milliseconds   I ve already 3 scripts  I saw an example like this     time     section code goes here     2 gt  timing log   But I only need the real time  not the user and sys  Also need it in a decent format  e g 00 00 00 00  not like the standard output    In other words  I d like to know how to turn the time output into something easier to process

User · Accepted Answer

You could use the date command to get the current time before and after performing the work to be timed and calculate the difference like this      bin bash    Get time as a UNIX timestamp  seconds elapsed since Jan 1  1970 0 00 UTC  T    date   s      Do some work here sleep 2  T       date   s -T    echo  Time in seconds    T    printf  Pretty format   02d  02d  02d  02d n      T 86400        T 3600 24        T 60 60        T 60       Notes           can be used for basic arithmetic in bash  ndash  caution  do not put spaces before a minus - as this might be interpreted as a command-line option   See also  http   tldp org LDP abs html arithexp html  EDIT  Additionally  you may want to take a look at sed to search and extract substrings from the output generated by time   EDIT     Example for timing with milliseconds  actually nanoseconds but truncated to milliseconds here   Your version of date has to support the  N format and bash should support large numbers     UNIX timestamp concatenated with nanoseconds T    date   s N      Do some work here sleep 2    Time interval in nanoseconds T       date   s N -T      Seconds S     T 1000000000      Milliseconds M     T 1000000     echo  Time in nanoseconds    T   printf  Pretty format   02d  02d  02d  02d  03d n      S 86400        S 3600 24        S 60 60        S 60       M     DISCLAIMER  My original version said  M     T 1000000000 1000000      but this was edited out because it apparently did not work for some people whereas the new version reportedly did  I did not approve of this because I think that you have to use the remainder only but was outvoted  Choose whatever fits you

User · Answer

Not quite sure what you are asking  have you tried   time yourscript   tail -n1  gt log   Edit  ok  so you know how to get the times out and you just want to change the format  It would help if you described what format you want  but here are some things to try   time -p script   This changes the output to one time per line in seconds with decimals  You only want the real time  not the other two so to get the number of seconds use   time -p script   tail -n 3   head -n 1

User · Answer

To use the Bash builtin time rather than  bin time you can set this variable   TIMEFORMAT   3R    which will output the real time that looks like this   5 009   or  65 233   The number specifies the precision and can range from 0 to 3  the default    You can use   TIMEFORMAT   3lR    to get output that looks like   3m10 022s   The l  ell  gives a long format

User · Answer

From the man page for time    There may be a shell built-in called time  avoid this by specifying  usr bin time You can provide a format string and one of the format options is elapsed time - e g   E   usr bin time -f  E   CMD   Example       usr bin time -f  E  ls  tmp mako  res py  res pyc 0 00 01

User · Answer

Use the bash built-in variable SECONDS  Each time you reference the variable it will return the elapsed time since the script invocation   Example   echo  Start  SECONDS  sleep 10 echo  Middle  SECONDS  sleep 10 echo  End  SECONDS    Output    Start 0 Middle 10 End 20

User · Answer

The accepted answer gives me this output   bash date sh Time in seconds  51 date sh  line 12  unexpected EOF while looking for matching   quot   date sh  line 21  syntax error  unexpected end of file  This is how I solved the issue    bin bash  date1   date --date  now    s   date since epoch in seconds at the start of script somecommand date2   date --date  now    s   date since epoch in seconds at the end of script difference   echo  quot    date2- date1   quot     difference between two values date3   echo  quot scale 2    difference 3600 quot    bc    difference 3600   seconds in hours echo SCRIPT TOOK  date3 HRS TO COMPLETE   3rd variable for a pretty output

[bash] Custom format for time command

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