Using a file input as stdin for a shell script does not work

Question

I have the following script code:

test.sh

echo "BEGIN"
while read CMD <&1; do
    [ -z "$CMD" ] && continue
    case "$CMD" in
    start)
            echo "get_start"
            ;;
    stop)
            echo "get_stop"
            ;;
    *)
            echo "get_uknown_command"
            ;;
    esac
    echo "END";
done

When I run it with:

$./test.sh <input.txt

I get my script locked

input.txt

start
stop
sthh

Why my script is locked? How I can fix that?

BTW: If I enter the data manually then the script will not lock.

shx2 · Accepted Answer · 2013-07-12 10:56:15Z

3

What do you need the <&1 for? Remove it, and it works.

while read CMD; do

./test.sh  < input.txt 
BEGIN
get_start
END
get_stop
END
get_uknown_command
END

answered Jul 12, 2013 at 10:56

shx2

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2 Comments

MOHAMED Over a year ago

it works. thank you. Explaination why it does not work with 1?

MOHAMED Over a year ago

I was not careful when I used this code. <&1 means get from stdout. so my script is expecting input data from stdout and not form stdin. change it with <&0 will work.

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