Start Script

This is an overview of variables I use within my scripts. It makes it easier to start.

#!/bin/bash
########################################################################################################################
# Author : Sjoerd Hooft
# Date Initial Version: 11 July 2011
# Comments: sjoerd_ @ _warmetal.nl
#
# Description:
# This is the description for this script.
#
# Recommendations:
# The script is designed for a 120 column terminal.
# The running user must be root.
#
# Changes:
# Please comment on your changes to the script (your name and email address, line number, description):
# DATE - USERNAME - EMAILADDRESS - CHANGE DESCRIPTION
########################################################################################################################
 
# Debug option; uncomment for debugging
# set -x
 
# Script Variables
HOSTNAME_SHORT=`hostname -s`
BASEDIR=`dirname $0`
WHATAMI=`basename $0`
LOGFILE="$BASEDIR/$WHATAMI.log"
DATE=`date +%Y%m%d`
# Highlight output on screen
BOLD=`tput bold`
BOLDOFF=`tput sgr0`
# Send all output to logfile; disable if screen output is needed
exec > $LOGFILE 2>&1
 
# Mail Variables and Function
MAILTOSUCCESS="sjoerd_warmetal.nl"
MAILTOFAILURE="alarm_warmetal.nl"
MAILTOALARM="alarm_warmetal.nl sjoerd_warmetal.nl"
MAILTOALARMCC="ccmail1_warmetal.nl ccmail2@warmetal.nl"
MAILSTATUS=success
 
mailFunction() {
   if [[ "$MAILSTATUS" -eq "success" ]]; then
      cat $LOGFILE | mail -s "Success $WHATAMI on $HOSTNAME_SHORT at $DATE" $MAILTOSUCCESS
   fi
   if [[ "$MAILSTATUS" -eq "failed" ]]; then
      cat $LOGFILE | mail -s "Failed $WHATAMI on $HOSTNAME_SHORT at $DATE" $MAILTOFAILURE
   fi
   if [[ "$MAILSTATUS" -eq "alarm" ]]; then
      cat $LOGFILE | mail -s "ALARM FOR $WHATAMI ON $HOSTNAME_SHORT AT $DATE" -c $MAILTOALARMCC $MAILTOALARM
   fi
}
 
# Start your script here

Snippet Pause the Script

# Function to pause the script
# The operator can evaluate the outcome of the previous function
scriptContinue () {
   if [ "$AUTOMATIC" == "0" ]; then
      echo "Press ENTER to continue"
      read CONTINUE
      clear
   fi
}

Snippet Script Usage

# Function to show how to use the script if the operator forgot script arguments
usageCommand() {
   echo
   echo "Usage $0 COMMAND:"
   echo "--------------------------------------"
   echo "$BOLD $0 <required arguments> $BOLDOFF"
   echo "--------------------------------------"
   echo
   echo argument: syntax
   echo
}
 
case "$1" in
 
argument )
   echo "You choose option $1"
   # Start your script here
;;
 
* )
   usageCommand
   exit 1
;;
 
esac

Script Variables

$$ = The PID number of the process executing the shell.
$? = Exit status variable.
$0 = The name of the command you used to call a program.
$1 = The first argument on the command line.
$2 = The second argument on the command line.
$n = The nth argument on the command line.
$* = All the arguments on the command line.
$# = The number of command line arguments.

The “shift” command can be used to shift command line arguments to the left, ie $1 becomes the value of $2, $3 shifts into $2, etc. The command, “shift 2” will shift 2 places meaning the new value of $1 will be the old value of $3 and so forth.

If possibillities

[ -a FILE ]	True if FILE exists.
[ -b FILE ]	True if FILE exists and is a block-special file.
[ -c FILE ]	True if FILE exists and is a character-special file.
[ -d FILE ]	True if FILE exists and is a directory.
[ -e FILE ]	True if FILE exists.
[ -f FILE ]	True if FILE exists and is a regular file.
[ -g FILE ]	True if FILE exists and its SGID bit is set.
[ -h FILE ]	True if FILE exists and is a symbolic link.
[ -k FILE ]	True if FILE exists and its sticky bit is set.
[ -p FILE ]	True if FILE exists and is a named pipe (FIFO).
[ -r FILE ]	True if FILE exists and is readable.
[ -s FILE ]	True if FILE exists and has a size greater than zero.
[ -t FD ]	True if file descriptor FD is open and refers to a terminal.
[ -u FILE ]	True if FILE exists and its SUID (set user ID) bit is set.
[ -w FILE ]	True if FILE exists and is writable.
[ -x FILE ]	True if FILE exists and is executable.
[ -O FILE ]	True if FILE exists and is owned by the effective user ID.
[ -G FILE ]	True if FILE exists and is owned by the effective group ID.
[ -L FILE ]	True if FILE exists and is a symbolic link.
[ -N FILE ]	True if FILE exists and has been modified since it was last read.
[ -S FILE ]	True if FILE exists and is a socket.
[ FILE1 -nt FILE2 ]	True if FILE1 has been changed more recently than FILE2, or if FILE1 exists and FILE2 does not.
[ FILE1 -ot FILE2 ]	True if FILE1 is older than FILE2, or is FILE2 exists and FILE1 does not.
[ FILE1 -ef FILE2 ]	True if FILE1 and FILE2 refer to the same device and inode numbers.
[ -o OPTIONNAME ]	True if shell option “OPTIONNAME” is enabled.
[ -z STRING ]	True of the length if “STRING” is zero.
[ -n STRING ] or [ STRING ]	True if the length of “STRING” is non-zero.
[ STRING1 == STRING2 ]	True if the strings are equal. ”=” may be used instead of ”==” for strict POSIX compliance.
[ STRING1 != STRING2 ]	True if the strings are not equal.
[ STRING1 < STRING2 ]	True if “STRING1” sorts before “STRING2” lexicographically in the current locale.
[ STRING1 > STRING2 ]	True if “STRING1” sorts after “STRING2” lexicographically in the current locale.
[ ARG1 OP ARG2 ]	“OP” is one of -eq, -ne, -lt, -le, -gt or -ge. These arithmetic binary operators return true if “ARG1” is equal to, not equal to, less than, less than or equal to, greater than, or greater than or equal to “ARG2”, respectively. “ARG1” and “ARG2” are integers.
[ ! EXPR ]	True if EXPR is false.
[ ( EXPR ) ]	Returns the value of EXPR. This may be used to override the normal precedence of operators.
[ EXPR1 -a EXPR2 ]	True if both EXPR1 and EXPR2 are true.
[ EXPR1 -o EXPR2 ]	True if either EXPR1 or EXPR2 is true.
command	True if command returns a 0 (zero).

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