file descriptor measurement tool

fdstat

#!/usr/bin/env bash

fdsta_main () {
  local num=${1:-5}
  local user=${2:-$USER}

  fds "$num" "$user"
}

fds() {
  local num=$1
  local user=$2
  local -A fdh=()
  local IFS=$IFS
  local command
  local count
  local max
  local old_IFS=$IFS
  local open
  local pid
  local pids=()
  local result
  local results=()
  local sum=0

  read -rd '' -a pids <<<"$(ps -U "$user" -o pid | tail -n +2)" ||:
  shopt -s nullglob
  for pid in "${pids[@]}"; do
    dir=/proc/$pid/fd
    count=$(set -- $(wc -w <(echo "$dir"/*)); echo "$1")
    (( count )) || continue
    fdh[$pid]=$count
    : $(( sum += $count ))
  done
  shopt -u nullglob
  for pid in "${!fdh[@]}"; do
    results+=( "$(printf '%s %s' "${fdh[$pid]}" "$pid")" )
  done
  IFS=$'\n'
  results=( $(sort -rn <<<"${results[*]}") )
  IFS=$old_IFS
  pids=()
  for result in "${results[@]}"; do
    pids+=( "$(set -- $result; echo "$2")" )
  done
  printf '  FDS     PID  CMD\n-----  ------  ---\n'
  results=()
  for pid in "${pids[@]:0:$num}"; do
    command=$(ps -p "$pid" -o cmd=)
    (( ${#command} > 300 )) && command=${command:0:300}...
    results+=( "$(printf '%05s  %06s  %s' "${fdh[$pid]}" "$pid" "$command")" )
  done
  printf '%s\n\n' "${results[@]}"
  printf '\nTotal file descriptors for user %s: %s\n' "$user" "$sum"
  result=$(< /proc/sys/fs/file-nr)
  open=$(set -- $result; echo "$1")
  max=$(set -- $result; echo "$3")
  printf 'System-wide open file descriptors: %s\n' "$open"
  printf 'System-wide max file descriptors: %s\n\n' "$max"
} 
    
strict_mode () {
  case $1 in
    'on' )
      set -o errexit
      set -o nounset
      set -o pipefail
      ;;
    'off' )
      set +o errexit
      set +o nounset
      set +o pipefail
      ;;
    * ) return 1;;
  esac
} 

return 0 2>/dev/null ||:

strict_mode on
fdsta_main "$@"