CODEWITHSUNDEEP
bash
GZ_0
GZ_0

Reputation: 27

Bash script seemingly stops working after a few hours

So, this script runs for a few hours, but suddenly stops doing its job. According to top it's still running, but it no longer seems to do anything.

WANSTAT=1
LTESTAT=1

tail -f /var/log/messages | grep --line-buffered mwan3 | while read -r INPUT ; do
    if [[ "$INPUT" == *"notice mwan3track[]: Interface wan (eth1) is offline" ]]; then
    WANSTAT=0
    echo "WAN offline"
    elif [[ "$INPUT" == *"notice mwan3track[]: Interface lte (3g-lte) is offline" ]]; then
    LTESTAT=0
    echo "LTE offline"
    elif [[ "$INPUT" == *"ifup interface wan (eth1)" ]]; then
    WANSTAT=1
    elif [[ "$INPUT" == *"ifup interface lte (3g-lte)" ]]; then
        LTESTAT=1
    fi
    if [ $WANSTAT -eq 0 ] && [ $LTESTAT -eq 0 ]; then
        echo "All red\n"
    elif [ $WANSTAT -eq 0 ]; then
        echo "WAN red, LTE green\n"
    elif [ $LTESTAT -eq 0 ]; then
        echo "LTE red, WAN green\n"
    else
        echo "All green\n"
    fi

done

Upvotes: 0

Views: 78

Answers (1)

chepner
chepner

Reputation: 531125

After a few hours, the logging system closes /var/log/messages, renames it, and opens a new file with the same name. tail -f, however, continues to watch the original file, which is no longer written to.

Use tail -F instead to ensure that you continue to watch the file named /var/log/messages, regardless of which file that actually is.

Upvotes: 5

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