How to Redirect the Output of the Time Command to a File in Linux

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

Try

{ time sleep 1 ; } 2> time.txt

which combines the STDERR of "time" and your command into time.txt

Or use

{ time sleep 1 2> sleep.stderr ; } 2> time.txt

which puts STDERR from "sleep" into the file "sleep.stderr" and only STDERR from "time" goes into "time.txt"

Redirecting the output of time command to a file

You're using bash, which indeed has a built-in keyword called time which functions in a similar way.

Instead of using the built-in time (bash) command, you can access the installed binary (if any) like /usr/bin/time -p [command] >file 2>&1. Which will exactly do what you expect.
Please note the -p option, which is needed for the "portable output format" you've seen above.

Also please take a look at the manpage: man time.

How can I redirect the output of the time command?

you can redirect the time output using,

(time ls) &> file

Because you need to take (time ls) as a single command so you can use braces.

How to redirect the output of time command to a log file?

time command is shell keyword... when your run time command in terminal it's not /usr/bin/time so the options like -a and -o will not work with time command. However man time will still display man page of /usr/bin/time .You have to use /usr/bin/time -o logfile command to redirect the time's output to file logfile or you can use the following command which is similar to shell's keyword time:

/usr/bin/time -o time_log -f "%E real,%U user,%S sys" [command] [args] to redirect the time's output to file time_log

how to redirect result of linux time command to some file

You can direct the stdout output of any commmand to a file using the > character.
To append the output to a file use >>

Note that unless done explicitly, output to stderr will still go to the console. To direct both stderr and stdout to the same output stream use

   command 2>&1 outfile.txt (with bash)

or

   command >& outfile.txt (with t/csh)

If you are working with bash All about redirection will give you more details and control about redirection.

Output time to a file with the Unix time command, but leave the output of the command to the console

The time command is tricky. The POSIX specification of time
doesn't define the default output format, but does define a format for the -p (presumably for 'POSIX') option. Note the (not easily understood) discussion of command sequences in pipelines.

The Bash specification say time prefixes a 'pipeline', which means that time cmd1 | cmd2 times both cmd1 and cmd2. It writes its results to standard error. The Korn shell is similar.

The POSIX format requires a single space between the tags such as real and the time; the default format often uses a tab instead of a space. Note that the /usr/bin/time command may have yet another output format. It does on macOS, for example, listing 3 times on a single line, by default, with the label after the time value; it supports -p to print in an approximation to the POSIX format (but it has multiple spaces between label and time).

You can easily get all the information written to standard error into a file:

(time my_command) 2> log.file

If my_command or any programs it invokes reports any errors to standard error, those will got to the log file too. And you will get all three lines of the output from time written to the file.

If your shell is Bash, you may be able to use process substitution to filter some of the output.

I wouldn't try it with a single command line; the hieroglyphs needed to make it work are ghastly and best encapsulated in shell scripts.

For example, a shell script time.filter to capture the output from time and write only the real time to a log file (default log.file, configurable by providing an alternative log file name as the first argument

#!/bin/sh

output="${1:-log.file}"
shift
sed -E '/^real[[:space:]]+(([0-9]+m)?[0-9]+[.][0-9]+s?)/{ s//\1/; w '"$output"'
        d;}
        /^(user|sys)[[:space:]]+(([0-9]+m)?[0-9]+[.][0-9]+s?)/d' "$@"

This assumes your sed uses -E to enable extended regular expressions.
The first line of the script finds the line containing the real label and the time after it (in a number of possible formats — but not all). It accepts an optional minutes value such as 60m05.003s, or just a seconds value 5.00s, or just 5.0 (POSIX formats — at least one digit after the decimal point is required). It captures the time part and prints it to the chosen file (by default, log.file; you can specify an alternative name as the first argument on the command line). Note that even GNU sed treats everything after the w command as file name; you have to continue the d (delete) command and the close brace } on a newline. GNU sed does not require the semicolon after d; BSD (macOS) sed does. The second line recognizes and deletes the lines reportin the user and sys times. Everything else is passed through unaltered.

The script processes any files you give it after the log file name, or standard input if you give it none. A better command line notation would use an explicit option (-l logfile) and getopts to specify the log file.

With that in place, we can devise a program that reports to standard error and standard output — my_command:

echo "nonsense: error: positive numbers are required for argument 1" >&2
dribbler -s 0.4 -r 0.1 -i data -t
echo "apoplexy: unforeseen problems induced temporary amnesia" >&2

You could use cat data instead of the dribbler command. The dribbler command as shown reads lines from data, writes them to standard output, with a random delay with a gaussian distribution between lines. The mean delay is 0.4 seconds; the standard deviation is 0.1 seconds. The other two lines are pretending to be commands that report errors to standard error.

My data file contained a nonsense 'poem' called 'The Great Panjandrum'.

With this background in place, we can run the command and capture the real time in log.file, delete (ignore) the user and system time values, while sending the rest of standard error to standard error by using:

$ (time my_command) 2> >(tee raw.stderr | time.filter >&2)

nonsense: error: positive numbers are required for argument 1
So she went into the garden
to cut a cabbage-leaf
to make an apple-pie
and at the same time
a great she-bear coming down the street
pops its head into the shop
What no soap
So he died
and she very imprudently married the Barber
and there were present
the Picninnies
and the Joblillies
and the Garyulies
and the great Panjandrum himself
with the little round button at top
and they all fell to playing the game of catch-as-catch-can
till the gunpowder ran out at the heels of their boots
apoplexy: unforeseen problems induced temporary amnesia


$ cat log.file

0m7.278s

(The time taken is normally between 6 and 8 seconds. There are 17 lines, so you'd expect it to take around 6.8 seconds at 0.4 seconds per line.) The blank line is from time; it is pretty hard to remove that blank line, and only that blank line, especially as POSIX says it is optional. It isn't worth it.

Save the output of the time command to a log file

I got using parenthesis

#!/bin/bash
HEX_ROOT=.
HEX_COLOURS=./data
HEX_PDB=.
HEX_MACROS=.
HEX_CACHE=./data

(time ./hex6i.x64 -kill -nogui -ncpu 1 -ngpu 1 -e dock.mac -l job.log) &> job.log

time + sftp commands script: how to correctly redirect output to log file

Script may be an option here and so:

script -c ./sftp_test.sh /mylogpath/sftp_test.log

The -c flag signifies to run a command in a non-interactive environment.

Is there a way to pipe output of time command into a log file?

At least on recent Linux distributions, the time command supports the -o FILE option:

/usr/bin/time -v -o time.log java RandomTest

Extracting output of Linux time command into a file

GNU time has -o FILE parameter that you can use to output the timing into a file. You can process the file, extract the timing from the file and put it somewhere in CSV or such in a loop.

It also has -f format option that lets you customize the output format of the time.

So, in your case it could go like this:

/usr/bin/time -o mytime.log -f "%e" scp -i k30.pem ubuntu@ec2-XX-YY-ZZ-WW.compute-1.amazonaws.com:/home/ubuntu/pics/* /home/pi/

In this command the "%e" format makes the GNU time print only elapsed real time in seconds.

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