How to get command output into function in bash?

Question

I'm trying to write simple script that compress specific directory periodically. Here is my code

#!/bin/bash
exec &> zipLogFile.log

log(){
CURRENT_TIME=$(date '+%Y-%m-%d %H:%M:%S')
if [ -n "$1" ]
then
        LEVEL=${1}
        MESSAGE=${2}
        echo "$LEVEL  $CURRENT_TIME  $MESSAGE"
else
        read IN
        LEVEL="INFO"
        echo "$LEVEL  $CURRENT_TIME  $IN"
fi
}

YESTERDAY=$(date -d "yesterday" '+%Y%m%d')
ROOT="/home/ubuntu/test"
YESTERDAY_DIR=$ROOT"/"$YESTERDAY

log "INFO" "checking directory $YESTERDAY_DIR"
if [ -d "$YESTERDAY_DIR" ]; then
        zip -r $ROOT"/"$YESTERDAY".zip" $ROOT"/"$YESTERDAY | log
        log "INFO" "Zip file $YESTERDAY_DIR.zip has been created"
else
        log "ERROR" "$YESTERDAY_DIR not exist."
fi

My problem is I want to get zip command's output to log function and print it from function. When I try to use pipe, it prints only first line of output and break zip command. Here is what I get in my logFile when I run script.

INFO  2017-05-21 15:09:22  checking directory /home/ubuntu/test/20170520
INFO  2017-05-21 15:09:22  adding: home/ubuntu/test/20170520/ (stored 0%)
INFO  2017-05-21 15:09:22  Zip file /home/ubuntu/test/20170520.zip has been created

What am I doing wrong here? Thanks for the help.

Eric Renouf · Accepted Answer · 2017-05-21 12:37:47Z

2

read will only read the first line, so your function then returns. When zip next tries to write to that pipe it finds that the pipe has been closed (because the function exited) and itself exits.

Instead, you could read in a loop (assuming you want to use only the time at the start of the function):

else
    while read -r line; do
        printf '%s %s %s\n' "$LEVEL" "$CURRENT_TIME" "$line"
    done
fi

which you could actually just do with sed like

else
    sed -e "s/^/$LEVEL $CURRENT_TIME /"
fi

If you want the time for each line, you'll have to get the date on each iteration of the loop:

else
    while read -r line; do
        printf '%s %s %s\n' "$LEVEL" "$(date '+%Y-%m-%d %H:%M:%S')" "$line"
    done
fi

answered May 21, 2017 at 12:37

Eric Renouf

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