In shell script condition check is very easy and simple using if else statements. Here is a example which we would like to discuss with our readers.
Scenario: We have a variable that contains long string value, user wants to find matching value from given string and perform check whether that text/character has matched from string value or or not.
#Program in Bash ShellLine 1: CHECK_SOURCE="[main] INFO com.adobe.jcr.checknode.existence - Node does not exist"line 2: echo $CHECK_SOURCE | grep -w -o -i 'Node exists'Line 3: if [ $? == 0 ]; thenLine 4: echo " matched"Line 5: elseLine 6: echo "not matched"
Line 7: fi
Explanation:
In line 1 we have declared a variable CHECK_SOURCE which have some value.
In line 2 we are finding text "Node exists" in value of variable CHECK_SOURCE using grep command.
In line 3 using if statement we are checking number of matches from last executed statement. $? sign will return number of matches. If text passed in grep command will find some matching text in variable then $? will number of matching otherwise it will return zero.