On , I learnt ...
$SECONDS shell variable
Bash provides a
$SECONDS environment variable which, if used in a script,
returns the number of seconds since the script was started.
SECONDS Each time this parameter is referenced, the number of seconds since shell invocation is returned. If a value is assigned to SECONDS, the value returned upon subsequent references is the number of seconds since the assignment plus the value assigned. The number of seconds at shell invocation and the current time is always determined by querying the system clock. If SECONDS is unset, it loses its special properties, even if it is subsequently reset.
Here’s a neat way of employing it with the
timeout command, taking from
Shell Scripting: Expert Recipes for Linux, Bash and More
#!/bin/bash # Reset timer. SECONDS=0 # Run slow command with a max execution time of 60 seconds and capture the exit # code. timeout 60s slow_command timeout_res=$? # The exit code will be 124 if the timeout was reached but we need to be # careful of the scenario where the `slow_command` exited within 60 seconds # with a code of 124. We use the `$SECONDS` timer to do that. if [ "$SECONDS" -lt "60" ]; then # Command did not time out; the exit code is from `slow_command`. echo "The command did not time out; it returned after $SECONDS seconds." else # Command did time out. echo "The command timed out." fi