Using Bash to display a progress indicator [duplicate]

Question

Using a bash only script, how can you provide a bash progress indicator?

For example, when I run a command from bash - while that command is executing - let the user know that something is still happening.

Answer 1

In this example using SCP, I'm demonstrating how to grab the process id (pid) and then do something while that process is running.

This displays a simple spinnng icon.

/usr/bin/scp [email protected]:file somewhere 2>/dev/null & pid=$! # Process Id of the previous running command  spin[0]="-" spin[1]="\\" spin[2]="|" spin[3]="/"  echo -n "[copying] ${spin[0]}" while [ kill -0 $pid ] do   for i in "${spin[@]}"   do         echo -ne "\b$i"         sleep 0.1   done done 

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William Pursell's solution

/usr/bin/scp [email protected]:file somewhere 2>/dev/null & pid=$! # Process Id of the previous running command  spin='-\|/'  i=0 while kill -0 $pid 2>/dev/null do   i=$(( (i+1) %4 ))   printf "\r${spin:$i:1}"   sleep .1 done