CODEWITHSUNDEEP
bashshellunix
LamaEu
LamaEu

Reputation: 71

Comparing strings case-insensitively

I want to compare Hello World to hello world. The result should be true, as if they were equal. I'm doing:

while read line; do

    newLine="$newLine$line"
done < $1

newp="Hello World"
if (( ${newp,,}==${newLine,,} )); then
    echo "true"
else
    echo "false"

fi

when I pass a text file consisting of:

#filename: file.txt

hello world

The output seems to be:

./testScript.txt: line 20: 0à»: hello world==hello world : syntax error in expression (error token is "world==hello world ")
+ echo false

What am I doing wrong here? Also, a bit unrelated, is there any way to pass the line that is in file.txt to a string(newLine) without doing that while I have done?

Upvotes: 1

Views: 83

Answers (2)

Benjamin W.
Benjamin W.

Reputation: 52102

There is a shell option, nocasematch, that enables case insensitive pattern matching for use with [[ and case.

Comparing strings that differ by casing only:

$ var1=lowercase
$ var2=LOWERCASE
$ [[ $var1 == $var2 ]] && echo "Matches!" || echo "Doesn't match!"
Doesn't match!

Now enabling the shell option and trying again:

$ shopt -s nocasematch
$ [[ $var1 == $var2 ]] && echo "Matches!" || echo "Doesn't match!"
Matches!

Just make sure to turn it off again with shopt -u nocasematch if you don't want to do all comparisons case insensitive.

Upvotes: 0

Some dude
Some dude

Reputation: 587

You should add commas and change the double parentheses to single brackets. The if statement should be something like:

if [ "${newp,,}" = "${newLine,,}" ]; then

And in relation to that while loop... It depends on what you want to do. If, like in this case, you want to get the entire file and save it as a single string, you could simply do:

line=$(cat $1)

I would suggest you only use that loop you wrote if you are trying to parse the file line by line, i.e. adding if statements, using different variables and so on. But for a simple case like this one, cat will do just fine.

Upvotes: 7

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