using functions with loop in bash

Question

Having this odd issue with a simple bash script:

#!/bin/bash

function printLinesFromInput {
    COUNTER=1
    while read USER; do 
        echo "Hello $USER"; 
        echo
    done < $1
}

while read USER; do 
    echo "Hello $USER"; 
done < south-park.txt

echo
echo "In function:"
echo $(printLinesFromInput south-park.txt)

It prints:

$ ./readFile.sh
Hello Eric
Hello Kyle
Hello Stan
Hello Kenny

In function:
 Hello Kenny

The function is not echoing all four lines of the file. I am wondering why is this the case. The input file south-park.txt is:

Eric
Kyle
Stan
Kenny

I gave this a shot, but was not able to reproduce your problem on Bash 4.4.12 in Cygwin; the "in function" output was Hello Eric Hello Kyle Hello Stan Hello Kenny as expected (on one line because of $()). — Jeff Bowman
– Jeff Bowman, Commented Mar 7, 2018 at 6:53

tshiono · Accepted Answer · 2018-03-07 06:58:49Z

1

I suppose the input file south-park.txt may contain CR LF line breaks. Try to say:

 ./readFile.sh | less

Then you'll see:

Hello Eric
Hello Kyle
Hello Stan
Hello Kenny

In function:
Hello Eric^M Hello Kyle^M Hello Stan^M Hello Kenny

To fix it, remove \r's in your input file or modify the function as:

function printLinesFromInput {
    COUNTER=1
    while read USER; do
        echo "Hello $USER" | tr -d '\r'
    done < $1
}

BTW if you want to insert line breaks between users, you'll need another trick :-).

answered Mar 7, 2018 at 6:58

tshiono

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