Shell

Wormhole: vagrant & PuPHPet

1 id & group

• [1] id
  • check whether the specified id exists
• [2] groups
  • [2.1]list groups OR check a specified group

  • [2.2]check whether a given user belong to a specified group

      =======================[1]================================
      id $UCD_USER > /dev/null 2>&1
      ======================[2.1]===============================
      if [ "${p:agent/sys.os.name}" = "AIX" ]; then
          lsgroup $UCD_GROUP > /dev/null 2>&1
      else
          getent group $UCD_GROUP > /dev/null 2>&1
      fi
      ======================[2.2]===============================
      id -nG "$IMP_USER" | grep -q "$UCD_GROUP"
    

2 Shell Pattern Matching

- [shopt -s extglob](http://www.gnu.org/software/bash/manual/html_node/Pattern-Matching.html#Pattern-Matching)
- [shopt: This builtin allows you to change additional shell optional behavior.](http://www.gnu.org/software/bash/manual/html_node/The-Shopt-Builtin.html)
- [usage] shopt [-pqsu] [-o] [optname …]
	- "-s" Enable (set) each optname
	- "-u" Disable (unset) each optname.
	- "-q" Suppresses normal output
	- "-o" Restricts the values of optname to be those defined for the -o option to the set builtin

3 Set Command

- set -o pipefail
	- If set, the return value of a pipeline is the value of the last (rightmost) command to exit with a  non-zero  status,or zero if all commands in the pipeline exit successfully.  This option is disabled by default.

	===========================3=================================
	#!/bin/bash

	ls ./a.txt |echo "hi" >/dev/null
	echo $? #0

	####################################
	set -o pipefail
	ls ./a.txt |echo "hi" >/dev/null
	echo $? #2

[Quick Reference] (https://help.ubuntu.com/community/CronHowto)

4 Crontab Job

• [Edit] crontab -e
• [Change Editor] select-editor
• [Test] Add new line: */2 * * * * date » ~/time.log

• [Start] sudo service cron restart

            *     *     *   *    *        command to be executed
            -     -     -   -    -
            |     |     |   |    |
            |     |     |   |    +----- day of week (0 - 6) (Sunday=0)
            |     |     |   +------- month (1 - 12)
            |     |     +--------- day of        month (1 - 31)
            |     +----------- hour (0 - 23)
            +------------- min (0 - 59)
  

5 file/text Tools

• awk
  • [What is it]
    • Stands for Aho,Weinberger, Kernighan
    • An AWK program is a sequence of pattern {action} pairs and function definitions.
  • [Format] awk ‘pattern + {action}’
    • [Note] One, but not both, of pattern {action} can be omitted.
  • [Action]
    • [Default Action] If {action} is omitted it is implicitly { print }.
    • [Short programs] are entered on the command line usually enclosed in ‘ ‘ to avoid shell interpretation.
    • [Longer programs] can be read in from a file with the -f option.
  • [Builtin-variables]
    • FS splits records into fields as a regular expression.
    • NR current record number in the total input stream.
    • NF number of fields in the current record.
    • $0 current record
    • $1-$N fields 1-N of current record
  • [Built-in functions]
    • gsub(r,s): replace r with s (default t is $0)
    • index(s,t)： return the first index # of s in t
    • length(s):
    • match(s,r): 0 not match, Returns the index of the first longest match
    • split(s,a,fs): String s is split into fields by REXPR r and the fields are loaded into array A.
    • substr(s,p):

  • [Program execution] BEGIN & END

      ========================Example====================
      ---------------------Default Root------------------
        if [ -f /etc/redhat-release ]; then
          APACHE_DEFAULT_DIR=$(grep -i '^DocumentRoot' /etc/httpd/conf/httpd.conf | awk '{print $2}' | sed sed 's/"//g')
        elif [ $(uname) = "AIX" ]; then
          APACHE_DEFAULT_DIR=$(grep -i '^DocumentRoot' /opt/freeware/etc/httpd/conf/httpd.conf | awk '{print $2}' | sed 's/"//g')
        elif [ $(uname) = "Linux" ]; then
          APACHE_DEFAULT_DIR=$(grep -i 'DocumentRoot' /etc/apache2/sites-available/\*default.conf | awk '{print $2}' | sed 's/"//g')
        fi
      -----------------------Show lines------------------
      // show the line 3 - 5
      $ cat hello.txt | awk 'NR==13, NR==19{print $1,$NF}'
          <Directory />
          Options FollowSymLinks
          AllowOverride All
          </Directory> </Directory>
    
          <Directory /home/ray/www>
      -----------------------Show fields-----------------
      // show the first column of line 3 - 5
      $ cat hello.txt | awk 'NR==13, NR==19{print $1}'
          <Directory
          Options
          AllowOverride
          </Directory>
    
          <Directory
      -----------------[Program execution]---------------
      cat hello.txt | awk ' BEGIN { count=0; } { count+=length($0); } END { print count; }'
      -------------------GET Inline----------------------
      #!/bin/bash
      echo | awk '{ while(getline < "date.txt") { print $0; } }'
      ------------------check dir empty------------------
      // Check if DIR is empty
      if [ $(ls -l "${DIR}" | awk 'NR==1 {print $2}') -eq 0 ]
    

6 Networks

• dig

7 compress & uncompress

			// uncompress
			sudo tar -zxvf v10.5fp6_linuxx64_server_t.tar.gz ./temp
			sudo tar -jxvf xx.tar.bz2

8 Install & Uninstall

• check installed app:
  • dpkg -l
• check app list
  • sudo apt-cache search all

9 environment

• User Env
  • ~/.profile
  • ~/.bash_profile OR ~./bash_login
  • ~/.bashrc
• System Env
  • /etc/environment
  • /etc/profile
  • /etc/bash.bashrc

10 remote tmux

ssh -t tmux attach-session -t

Common Commands

• 1 Find Non-response App

  • ps -ef

    grep skype

  • ps -aux

    grep skype

• 2 Get Substring
  • expr substr ‘this is an example’ 3 4