show the cmdline of the recursively by its ppid

Author: DingGuodong

functions/process/pstree2.sh

@@ -0,0 +1,44 @@
+#!/usr/bin/env bash
+# Program name: pstree2
+# Usage: bash $0 <pid>
+# Description: show the cmdline of the recursively by its ppid,
+#   like the `pstree` display a tree of processes but only show related items.
+# Author: dgden
+# Create Date: 2021/5/10
+# Create Time: 22:24
+
+
+#if [ "$(id -u)" != "0" ]; then
+#  echo "WARNING: This script should be run as root" 2>&1
+#fi
+
+[[ "$1" == "" ]] && echo "usage: show the ppid recursively of the pid, using with \"$0 <pid>\"" && exit 1
+
+current_pid="$1"
+
+# shellcheck disable=SC2001
+current_pid_grep=$(echo "$current_pid" | sed 's/^\(.\)/[\1]/')
+
+# shellcheck disable=SC2009
+ps -ef | grep "$current_pid_grep" | awk -v pid="$current_pid" '$2==pid' | grep "$current_pid_grep"
+
+# shellcheck disable=SC2009
+current_ppid="$(ps -ef | grep "$current_pid_grep" | awk -v ppid="$current_pid" '$2==ppid {print $3}')"
+
+if [[ "$current_ppid" == "" || "$current_ppid" == "0" ]]; then
+    echo "the pid not exists."
+    exit 1
+fi
+
+while [[ $current_ppid -ne 1 ]]; do
+  # shellcheck disable=SC2001
+  current_ppid_grep=$(echo "$current_ppid" | sed 's/^\(.\)/[\1]/')
+  # shellcheck disable=SC2009
+  ps -ef | grep "$current_ppid_grep" | awk -v pid="$current_ppid" '$2==pid'
+
+  # shellcheck disable=SC2009
+  current_ppid="$(ps -ef | grep "$current_ppid_grep" | awk -v ppid="$current_ppid" '$2==ppid {print $3}')"
+  if [[ $current_ppid -eq 1 ]]; then
+    break
+  fi
+done