A shell function that repeats an action until either some condition is met or timeout occurs. NOTE: blocking actions/condition checks will block the function

do_until.sh

## USAGE: 
##   do_until true "ls -l /var/run/dockerd.sock"
##   do_until true "ls -l /var/run/dockerd.sock 10 1"
##   a=5; do_until 'a=$((a+1))' 'echo "a=${a}"; [ ${a} -ge 10 ]' 7 1

do_until() { 
  local task=${1:?Task missing}; 
  local condition=${2:?Condition missing}; 
  local timeout=${3:-60}; 
  local pause=${4:-5}; 
  local end_at=$(($(date +%s)+timeout)); 
  local ret=;
  local now=;
  
  while [ -z "${ret}" ] ; do 
    eval "${task}"; 
    now=$(date +%s);
    if eval "${condition}" ; then 
      ret=0 ; 
    elif [ ${end_at} -le ${now} ] ; then 
      ret=1; 
    else 
      sleep ${pause}; 
    fi; 
  done; 
  
  return ${ret}; 
}