print line number of output in shell script - shell

Question

I have a script that prints out the average time when pinging a server, shown below:
ping -c3 "${I}" | tail -1 | awk '{print $4}' | cut -d '/' -f 2 | sed 's/$/\tms/'
How can I add the line number to output of the script above when pinging a list of servers ??
my actual output when pinging list of 3 host is:
6.924 ms
100.099 ms
7.756 ms
I want the output to be like this:
1,6.924 ms
2,100.099 ms
3,7,756 ms
so that this can be read by excel :)
Thank in advanced!!

Answer 1

Pipe your output through perl:
echo -e 'aa\nbb' | perl -ne 'print $., ",", $_'
Output:
1,aa
2,bb

Answer 2

Is that what you want?
C=1
for I in 'host1' 'host2' 'host3'
do
ping -c3 "${I}" | tail -1 | awk '{print $4}' | cut -d '/' -f 2 | echo "$C,$(sed 's/$/\tms/')"
C=$((C+1))
done

Answer 3

The standard tool for line numbering is nl. Pipe your output to nl -s, That is:
for I; do
ping -c3 "${I}" | awk -F/ 'END{print $5, "\tms"}'
done | nl -s,
Since you haven't specified how the list is generated, I'm just showing the case where the list of hosts to be pinged is given on the command line. Note that this introduces leading whitespace before the line number, so you might want to filter that through sed to remove.
Of course, this script is spending most of its time waiting for the ping, and you probably want to speed it up by running the pings in parallel. In that case, it is better to add the line number at the beginning so you can get a stable sort in the output:
line=1
{ for I; do ping -c3 $I | awk -F/ 'END{
printf( "%d,%s\tms\n", line,$5 )}' line=$line &
: $((line +=1 ))
done; wait; } | sort -n
In this case, the wait is not necessary since sort will block until all of the pings have closed their output, but the wait becomes necessary if you add any processes in the pipeline before the sort that do not necessarily wait for all of their input before doing any processing, so it is a good practice to leave the wait in place.