Running commands after event based outputs

Question

there are commands like

iwevent

or

tcpdump -n src host x.x.x.x

that send to the stdout some lines when something happens. Is there any form of running some command inmmediatly after a line is printed. Ex:

iwevent | echo "Wireless event happened"

glenn jackman · Accepted Answer · 2013-10-10 22:42:17Z

4

Just read stdin in a loop

iwevent | while IFS= read -r line; do
    echo "[$(date "+%F %T")] - $line"
done

Depending on what you do in the loop body, you might want

while IFS= read -r line; do
    echo "[$(date "+%F %T")] - $line"
done < <(iwevent)

That avoids the implicit subshell effects of using a pipeline.

answered Oct 10, 2013 at 22:42

glenn jackman

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Runium · Accepted Answer · 2013-10-10 22:42:31Z

3

Not sure I get what you mean, but something in the direction of this?

while IFS= read -r line; do
    printf "%s\n%s\n" "$line" "Yohooo! One more package."
done < <(tcpdump -i any -nS)

answered Oct 10, 2013 at 22:42

Runium

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2 Answers 2