CODEWITHSUNDEEP
linuxbashshellubuntu
Burro
Burro

Reputation: 65

How to store elapsed time of a variable assignment to another variable in bash script?

I wanted to run a maven command and store the console output to a variable and in turn, store the real time of the mentioned operation in another variable. I wrote the following command -

x1=`( time t1=$( mvn test -Drat.skip)) 2>&1 | grep real`

When I echo variable x1 I get 0m17.430s which is the desired output but when I echo variable t1 it prints nothing! How can I store the console output of mvn test -Drat.skip in t1?

Upvotes: 1

Views: 147

Answers (2)

Ivan
Ivan

Reputation: 7253

As @choroba said t1 is created in different subshell and can't be exported back. You cat test it like this:

t1=test
x1=`(time t1=$(echo ok); echo $t1) 2>&1`
echo $t1
echo $x1

The output will be:

$ echo $t1
test

$ echo $x1
real 0m0,001s user 0m0,001s sys 0m0,001s ok

But this litle hack may help

fun () { t1=$(mvn test -Drat.skip); }
x1=$((time fun) 2>&1 | grep real)

Upvotes: 1

choroba
choroba

Reputation: 241758

Everything inside of () or backticks happens in a subshell. Variable values aren't exported from a subshell back to the parent shell.

You can assign both the output of the command and output of time into a variable and then extract it from there:

#!/bin/bash
all=$((time mvn test -Drat.skip )2>&1)
time=$(tail -n3 <<< "$all" | grep real)
output=$(head -n-3 <<< "$all")

Upvotes: 3

Related Questions