Display Number of Open Filehandles in total or grouped by kind of Files, Sockets, Pipes, Anon_INodes, for all processes or a ceratain PID

nrof

#!/bin/bash
#
# 20141126/gj
# 20150219/gj	pipes
# 20190225/gj	'all' command
# 20191107/gj	add anon_inode
# 20191007/gj	get fd stats once
# 20200616/gj	get limits
# 20200806/gj	get limits via /etc/security/limits.conf because smnpd is startet with lower limits
# 20200919/gj	skip comments in limits.conf


COUNTHANDLES() { # $1: PID
  [ "$OPENTOTAL" ] && return	# evaluate once
  # evaluate all symbolic links
  while read _ _ NAME; do
    NAME=${NAME:1:-1}
    case "$NAME" in
    'anon_inode:'*) ((OPENANON_INODES++)) ;;
    'pipe:'*)       ((OPENPIPES++)) ;;
    'socket:'*)     ((OPENSOCKETS++)) ;;
    *)              ((OPENFILES++));;
    esac
  done < <(eval stat /proc/${1:-\{1..9\}*}/fd/* -c "%N" 2>/dev/null)
  OPENTOTAL="$((OPENFILES + OPENSOCKETS + OPENPIPES + OPENANON_INODES))"
}

READLIMIT() { # $1: KIND
  local KIND="$1"; shift
  sed 's/^[^#].*'$KIND'.*nofile\W*\(.*\)/\1/gp' -n /etc/security/limits.conf
}

DISPLAY() { #1: WHICH, #2: PID
  COUNTHANDLES $2
  OPENSOFTLIMIT="$(READLIMIT soft)"
  OPENHARDLIMIT="$(READLIMIT hard)"
  if [ "$1" ]; then
    echo "${!1}"
  else
    echo "total:$OPENTOTAL files:$OPENFILES sockets:$OPENSOCKETS pipes:$OPENPIPES anon_inodes:$OPENANON_INODES limit:$OPENSOFTLIMIT hard:$OPENHARDLIMIT"
  fi
}


KIND="$1"; shift
PID="$1"; shift
case "$KIND" in
'a'*) DISPLAY OPENANON_INODES $PID;;
'f'*) DISPLAY OPENFILES $PID;;
'h'*) DISPLAY OPENHARDLIMIT $PID;;
'l'*) DISPLAY OPENSOFTLIMIT $PID;;
'p'*) DISPLAY OPENPIPES $PID;;
's'*) DISPLAY OPENSOCKETS $PID;;
't'*) DISPLAY OPENTOTAL $PID;;
[0-9]*|'')
  PID=$KIND; KIND=''
  DISPLAY '' $PID
;;
*)
  cat >&2 <<-EOT
	syntax : $0 <f[iles],s[ocktes],p[ipes],a[non_inodes],l[imit],h[ardlimit]> [pid]
	         $0 t[otal] [pid]
	         $0 pid
	         $0 
	purpose: display number of open files for a kind or for all kinds
EOT
esac