using time command in bash script and redirect the output

Question

I'm trying to write a script that does

x =$ncore
numactrl -C $x ( time -p $exe ) > out.txt 2>&1

on the terminal ( time $ exe ) > out.txt 2>&1 worked as i wanted to (out.txt containing output of time and executable )

i'm using red hat 6.2 and time is not GNU version( i'm assuming from the fact that -a -o options don't work)

i want out.txt to have output from the executable and at the end have output from the time command.

the bash script is giving me problems with having ( so i used ( time -p $exe ) and now numactl sees ( as the executable.

is there a way to use numactl and time command together and have the output i want ?

Alan Curry · Accepted Answer · 2012-07-25 23:04:18Z

2

If numactrl wants a command, but you want to use some shell features, just give it the shell as a command:

numactrl -C $x bash -c "( time -p $exe ) > out.txt 2>&1"

When you runtime -p $exe from a bash prompt or within a bash -c, you're using the bash builtin version of time. The one with the -o option is an external command, so to use it from bash you have to specify command time or /bin/time or /usr/bin/time.

If you run numactrl -C $x time ... then it probably runs the external command, so -o should work in that case, but if not then you always have the bash -c method.

Note that the output format is different between the various versions of time. The GNU coreutils version prints more information than the bash builtin version.

answered Jul 25, 2012 at 23:04

Alan Curry

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