Bash while loop with substring condition

Question

I have a function with a while loop that should run untill it one of the string will be a substring of my second string. The thing is that the while loop is infinity, and i double checked my condition and it shouldn't go inside the while loop with the paramteres that i've entered. Here is my 2 functions:

## check if the client exist
## if exists return 1 else return 0
function isClientExist () {
        clientToCheck=irabinowitz_tlv-cc-lx64_806
        checkClient=$(p4 client -o -t $clientToCheck 2>&1)
        tempStr="doesn\'t exist"
        if [[ $checkClient != *"$tempStr"* ]]; then
                echo The client exist
                flag=1
        else
                echo the client doesnt exist
                clientToCreate=$clientToCheck
                flag=0
        fi
        return $flag
}
## Fixing the client name by appeding  _number to the client name
function fixClientName () {
        echo fixing the client name...
        numToAppend=1
        tempClientToCheck=$clientToCheck
        echo the temp client to check is: $tempClientToCheck
        clientToCheck+=_$numToAppend
        echo  the client to check is: $clientToCheck
        echo try number $numToAppend
        sleep 20
        while [[ $checkClient != *"$tempStr"* ]]; do

        #       let "numToAppend+1"
                ((++numToAppend))
                clientToCheck=$tempClientToCheck
                echo the client to check in the loop before appending  is: $clientToCheck
                clientToCheck+=_$numToAppend
                echo the client to check in the loop after appending is: $clientToCheck
                echo try number $numToAppend
                sleep 20

        done
        clientToCreate=$clientToCheck
        echo the client to create is $clientToCreate
}

#main
isClientExist
if [ $? -eq 1 ]; then
        fixClientName
fi

You have several problems here: for one, let "numToAppend+1" doesn't do what you think it does: it only returns success. Instead, you probably want ((++numToAppend)). Also, your line clientToCheck+=_$numToAppend will keep on appending: so before the while loop you have clientToCheck that expands to irabinowitz_tlv-cc-lx64_806_1, then, in the while loop you'll have irabinowitz_tlv-cc-lx64_806_1_2, irabinowitz_tlv-cc-lx64_806_1_2_3, etc. (assuming numToAppend gets incremented properly). Your design is also really weird. — gniourf_gniourf
– gniourf_gniourf, Commented Feb 1, 2015 at 16:03
Also in fixClientName you're never calling isClientExist. — gniourf_gniourf
– gniourf_gniourf, Commented Feb 1, 2015 at 16:08

rici · Accepted Answer · 2015-02-01 16:55:44Z

1

You should not backslash-escape the ' in:

tempStr="doesn\'t exist"

That will never match the string you expect, so [[ $checkClient != *"$tempStr"* ]]; will always succeed.

It won't match, because inside a double-quoted string, \' is, literally, \'. So the backslash would have to be in the message for the match to succeed.

Use one of the following:

tempStr="doesn't exist"
tempStr=doesn\'t\ exist

answered Feb 1, 2015 at 16:55

rici

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4 Comments

rici Over a year ago

@user3502786: You should learn how to use function parameters ($1, $2, ...) and local variables. And also, remember that if statement; tests whether statement succeeds or fails, so there is no need to play games with [[ and $? if you just want to know if a command succeeded or failed. But all of that belongs on codereview.stackexchange.com

gniourf_gniourf Over a year ago

@user3502786 if it “works” it's because isClientExist succeeds and the if branch is never executed. In a case where isClientExist fails, you'll run into an infinite loop since, as I said in a comment, your function fixClientName never updates checkClient, so you'll still get an infinite loop in that case.

Alex Brodov Over a year ago

I could place the fixClientName function inside the isClientExist function

Alex Brodov Over a year ago

The while loop still not working, it's never exisitng from the program, any idea how to solve it ?

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