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UNIX in a Nutshell: System V Edition

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The Bourne Shell and Korn Shell
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if



if

 

condition

1


then

 

commands1

 
[ 

elif

 

condition2


	

then

 

commands2

 ]
 .
 .
 .
[ 

else

 

commands3

 ]


fi

If condition1 is met, do commands1 ; otherwise, if condition2 is met, do commands2 ; if neither is met, do commands3 . Conditions are usually specified with the test command. See additional examples under : and exit .

Examples

Insert a 0 before numbers less than 10:

if [ $counter -lt 10 ]
then number=0$counter
else number=$counter
fi

Make a directory if it doesn't exist:

if [ ! -d $dir ]; then
   mkdir $dir
   chmod 775 $dir
fi


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