How to redirect the output of the time command to a file in Linux

Question

Just a little question about timing programs on Linux  the time command allows to measure the execution time of a program    ed lbox200     time sleep 1  real    0m1 004s user    0m0 000s sys     0m0 004s   Which works fine  But if I try to redirect the output to a file  it fails    ed lbox200     time sleep 1  gt  time txt  real    0m1 004s user    0m0 001s sys     0m0 004s   ed lbox200     cat time txt   ed lbox200        I know there are other implementations of time with the option -o to write a file but my question is about the command without those options   Any suggestions

User · Answer

amp  gt out time command  gt  dev null   in your case   amp  gt out time sleep 1  gt  dev null   then  cat out

User · Answer

Since the output of  time  command is error output  redirect it as standard output would be more intuitive to do further processing     time sleep 1    2 gt  amp 1    cat  gt  time txt

User · Answer

If you care about the command s error output you can separate them like this while still using the built-in time command     time your command 2 gt  command err     2 gt  time log   or    time your command 2 gt 1     2 gt  time log   As you see the command s errors go to a file  since stderr is used for time    Unfortunately you can t send it to another handle  like 3 gt  amp 2  since that will not exist anymore outside the        That said  if you can use GNU time  just do what  Tim Ludwinski said    time -o time log command

User · Answer

Wrap time and the command you are timing in a set of brackets   For example  the following times ls and writes the result of ls and the results of the timing into outfile      time ls   gt  outfile 2 gt  amp 1   Or  if you d like to separate the output of the command from the captured output from time      time ls   gt  ls results 2 gt  time results

User · Answer

If you are using GNU time instead of the bash built-in  try  time -o outfile command    Note  GNU time formats a little differently than the bash built-in

User · Answer

Try    time sleep 1     2 gt  time txt   which combines the STDERR of  time  and your command into time txt  Or use    time sleep 1 2 gt  sleep stderr     2 gt  time txt   which puts STDERR from  sleep  into the file  sleep stderr  and only STDERR from  time  goes into  time txt

User · Answer

bin bash  set -e   onexit             TMPD     amp  amp  rm -rf   TMPD     TMPD    mktemp -d   trap  onexit EXIT   time 2              2 gt  amp 3     time 1         time  time 2          time         declare time label   1      shift     exec 3 gt  amp 2      time 1      2 gt   TMPD timing  time label      echo  time  time label       cat   TMPD timing  time label      time a  do something  time b  do another thing  time c  finish up   This has the benefit of not spawning sub shells  and the final pipeline has it s stderr restored to the real stderr

User · Answer

If you want just the time in a shell variable then this works  var    time  lt command gt      2 gt  amp 1 1 gt  dev null

User · Answer

If you are using csh you can use    usr bin time --output outfile -p  SHELL  -c  your command    For example    usr bin time --output outtime txt -p csh -c  cat file

User · Answer

If you don t want to touch the original process  stdout and stderr  you can redirect stderr to file descriptor 3 and back       time   perl -le  print  foo   warn  bar    2 gt  amp 3       3 gt  amp 2 2 gt  time out foo bar at -e line 1    cat time out  real    0m0 009s user    0m0 004s sys     0m0 000s   You could use that for a wrapper  e g  for cronjobs  to monitor runtimes      bin bash  echo     date          gt  gt   my runtime log    time        2 gt  amp 3       3 gt  amp 2 2 gt  gt   my runtime log

User · Answer

I ended up using    usr bin time -ao output file txt -f  Operation took   E  echo lol    Where  a  is append Where  o  is proceeded by the file name to append to Where  f  is format with a printf-like syntax Where   E  produces 0 00 00  hours minutes seconds I had to invoke  usr bin time because the bash  time  was trampling it and doesn t have the same options I was just trying to get output to file  not the same thing as OP

User · Answer

Simple  The GNU time utility has an option for that   But you have to ensure that you are not using your shell s builtin time command  at least the bash builtin does not provide that option  That s why you need to give the full path of the time utility    usr bin time -o time txt sleep 1

[linux] How to redirect the output of the time command to a file in Linux?

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