Running a shell script for a certain duration

I want to be able to run a script on Linux shell (bash) for a certain duration and sleep for a different duration. I’ve written something like the following snippet. However, I see only the sleep happening correctly but the execution stops after first execution.

#!/bin/bash
some_work(){
    echo "Working for $1 minutes"
    if [ $1 -gt 0 ]
        then
            echo "Setting timer for $1 minutes"
            run_end_time=$(($1 * 60))
            start_time=SECONDS
            curr_time=SECONDS
            while $((curr_time < $((start_time + run_end_time)) )) :
                do
                    #Do some work here
                    curr_time=SECONDS
                done
    fi
}

sleep_time(){
    echo "Sleeping for $1 minutes"
    sleep $(($1 * 60))
}

if [ $# -gt 1 ]
    then
        echo "Starting Steeplechase run for $1/$2" 
        while :
            do
                some_work $1
                sleep_time $2
        done
fi

The response I get is ./script.sh: line 30: 1: not found. Maybe I’m missing something bigtime here.

Answer

A few issues:

• The conditional construct is while (( ... )); do and not while $(( ... )); do

• The colon at the end of your line

  while $((curr_time < $((start_time + run_end_time)) )) :
  

  must not be there.

• You’re assigning the string SECONDS when you want the value of the variable; the assignments should look like var=$SECONDS instead of var=SECONDS.

Complete script, with a few suggestions and my idea of indentation:

#!/bin/bash

some_work () {
    echo "Working for $1 minutes"
    if (( $1 > 0 )); then
        echo "Setting timer for $1 minutes"
        run_end_time=$(($1 * 60))
        start_time=$SECONDS
        curr_time=$start_time  # Want this to be the same value
        while ((curr_time < $((start_time + run_end_time)) )); do
            #Do some work here
            curr_time=$SECONDS
        done
    fi
}

sleep_time () {
    echo "Sleeping for $1 minutes"
    sleep $(($1 * 60))
}

if (( $# > 1 )); then
    echo "Starting Steeplechase run for $1/$2"
    while true; do
        some_work $1
        sleep_time $2
    done
fi