How to pass value to read variable with pipe (stdin) in bash

debugcn Published at Dev

FotisK

I read a lot about passing piping stdin to bash read function, but nothing seems to work for my bash version!!

GNU bash, version 3.2.51(1)-release (x86_64-suse-linux-gnu)

I have a bash script that in some point asks the user "yes/no" with variable CONTINUEQUESTION:

echo "Do you want to continue? (yes/no):"
read CONTINUEQUESTION
tmp=$(tr '[:upper:]' '[:lower:]' <<<$CONTINUEQUESTION)
if [[ "$tmp" != 'y'  &&  "$tmp" != 'yes' ]]; then
                echo "Aborting because of input '$CONTINUEQUESTION'"
                exit
fi

I would like to pipe a "yes or no" to this question without user input! Yes i know i could use expect, but i don't prefer it in this case.

So i tried several things:

CONTINUEQUESTION='yes'
echo $CONTINUEQUESTION | ./myscript.sh

Aborting because of input ''

./myscript.sh <<< "$CONTINUEQUESTION"

Aborting because of input ''

...and many other, nothing worked!?

O.k. now I did a bit revers thinking and find out that the below line causes the problem with the pipe...because when i remarked it out all the below answers are working just fine, but not when this line is executed:

running=`ssh root@${HOSTNAME} 'su - root -c "/bin/tools list | grep \"system running\"" 2>&1'`

But, i need this line before the read! What do i need to reverse the 2>&1????

My script look like this and is working without this try to over come the user intervantion:

LIST_FILE_NAME=$1
STILL_RUNNING=0

running=`ssh root@${HOSTNAME} 'su - root -c "cat '$LIST_FILE_NAME' | grep \"system running\"" 2>&1'`
if [[ $running =~ .*running.* ]]; then
        STILL_RUNNING=1
        echo "NODE $NODE running stop before continuing."
fi
if [ $STILL_RUNNING -eq 1 ]; then
        echo "Aborting system was still running!"
        exit 1
fi

echo "Do you want to continue? (yes/no):"
read CONTINUEQUESTION

tmp=$(tr '[:upper:]' '[:lower:]' <<<$CONTINUEQUESTION)
if [[ "$tmp" != 'y'  &&  "$tmp" != 'yes' ]]; then
                echo "Aborting because of input '$CONTINUEQUESTION'"
                exit
fi

echo "o.k."

4 points:

list.log can have a line with "system running" or "system notrunning"
if list.log has a line with "system notrunning" than the bash script continue towards the question
at the question i never got it right to inject the 'y' or 'yes' so the bash aborts because of input ''
i execute this like: ./myscript.sh list list.log (normal way)

This bash runs well if the user interacts at the question!

Thanks for you time!!!

konsolebox

Consider this variation as well:

#!/bin/bash
read -p "Do you want to continue? (yes/no): " CONTINUEQUESTION
if [[ $CONTINUEQUESTION != [Yy] && $CONTINUEQUESTION != [Yy][Ee][Ss] ]]; then
    echo "Aborting because of input '$CONTINUEQUESTION'."
    exit
fi

Tested with: