1. Shell Script Yingying Wang

2. Basic Commands

3. Good resources Google is your friend http://www.freeos.com/guides/lsst/

4. Example 1 $>nano hi.sh (or cat > hi.sh) #! /bin/bash echo “Hi Gaab Lab!” $>chmod u+x hi.sh $>./hi.sh (or sh hi.sh)

5. Example 2 $>cat > example2.sh if [ $# -ne 2 ] then echo "Usage - $0 x y" echo " Where x and y are two numbers for which I will print sum" exit 1 fi echo "Sum of $1 and $2 is `expr $1 + $2`“ Ctrl+D get out and return to command line $>chmod u+x example2.sh $>./example2.sh 1 2

6. Home Work Try to write a script to compute the sum for three numbers

7. Example 3 $>cat > example3.sh i=5 while test $i != 0 do echo "$i " i=`expr $i - 1` Done Ctrl+D get out and return to command line $>chmod u+x example3.sh $>./example3.sh

8. Example 4 #!/bin/bash echo "Hello, $LOGNAME" echo "Current date is `date`" echo "User is `who i am`" echo "Current direcotry `pwd`"

9. Example 5 #!/bin/bash if [ $# -ne 1 ] then echo "Usage - $0 file-name" exit 1 fi if [ -f $1 ] then echo "$1 file exist" else echo "Sorry, $1 file does not exist" fi

10. Example 6 #! /bin/bash TEST_DIR=/neuro/labs/gaablab if [ -d "$TEST_DIR" ]; then echo $TEST_DIR already exists. Exiting! exit fi

11. Example 7 x=/neuro/labs/test.nii.gz if [ ! -f "$x" ]; then Echo $x cannot be found exit Fi y=abc echo "$y" if [ -z "$y" ]; then echo yes fi

12. Warnings Don’t use “rm” and “rm -r” in your script when you’re not experienced programmer. Once, a student accidentally used “rm” command and deleted all the data collected over couple of years. THAT’S DISASTER.