CODEWITHSUNDEEP
bash
boaz
boaz

Reputation: 900

How to check if a line from a file is empty with bash

I have a while loop which reads lines from a file using read line. Then I want to check if the line is empty or not, how can I do it? I already found questions about lines with space or about a variable in this site.

Upvotes: 4

Views: 1225

Answers (2)

Andomar
Andomar

Reputation: 238086

The -n operator checks if a string is not empty:

while read line    
do
    if [ -n "$line" ]
        echo $line
    fi
done < file.txt

If you'd want to exclude strings containing only whitespace, you could use bash's pattern replacement ${var//find/replacement}. For example:

if -n [ "${line//[[:space:]]/}" ]

Upvotes: 1

codaddict
codaddict

Reputation: 455020

You can use the test:

[ -z "$line" ]

From the bash man page:

-z string
True if the length of string is zero.

Upvotes: 7

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