Checking input with an if statement (bash)

Question

I am trying to write a file that mimics the cat -n bash command. It is supposed to accept a filename as input and if no input is given print a usage statement.

This is what I have so far but I am not sure what I am doing wrong:

#!/bin/bash
echo "OK"
read filename
if [ $filename -eq 0 ]
then 
    echo "Usage: cat-n.sh file"
else
    cat -n $filename
fi

Cyrus · Accepted Answer · 2016-09-29 02:08:54Z

2

I suggest to use -z to check for empty variable $filename:

if [ -z $filename ]

See: help test

answered Sep 29, 2016 at 2:08

Cyrus

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1 Comment

John1024 Over a year ago

Or -f to test for the existence of a regular file or -r to verify that it is readable.

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