I have two commands say cmd1 and cmd2, wherein i perform
time cmd1 | cmd2
I want to get something like
cmd1 >> file.out and {time cmd1 >> file.out} | cmd2 >> file.out
so can someone suggest how it is actually done? edit: as Anthony's answer below suggests, tee works here but if i write
time cmd1 |tee -a file.out | cmd2 >> file.out
then it only writes the output of cmd1 to file.out and cmd2 to file.out, whereas i also want the output of {time cmd1} to that file.
I am using bash shell on Ubuntu Mate. If the time keyword complicates it, please suggest some method to time the execution and do the exact operation.
If I understand your question correctly, you want the output of cmd to be
written to file.out and also used as the input to cmd2. For this case, you could try inserting the tee command (with the -a option to append) into your command pipeline:
cmd1 | tee -a file.out | cmd2 >> file.out
$ printf "one\ntwo\nthree\n" | tee -a file.out | sed 's/.*/\U&/' >> file.out
$ cat file.out
one
two
three
ONE
TWO
THREE
The following construct should do what you want:
{ time cmd1; } 2>> file.out | tee -a file.out | cmd2 >> file.out
Since the time utility provided by Bash operates on the complete pipeline, curly braces are used to group these commands so that they can be considered as a whole. Note: the terminating semi-colon (;) is required before the closing brace.
The standard out stream of cmd1 is piped through to the tee command but since Bash’s time utility prints its timing statistics to standard error, the file descriptor 2 is redirected so that the timing statistics are appended to file.out.
{ time printf "one\ntwo\nthree\n"; } 2>> file.out | tee -a file.out | sed 's/.*/\U&/' >> file.out