bash script split array of strings to designed output

Question

Data in log file is something like:

"ipHostNumber: 127.0.0.1
ipHostNumber: 127.0.0.2
ipHostNumber: 127.0.0.3"

that's my code snippet:

readarray -t iparray < "$destlog"
unset iparray[0]

for ip in "${iparray[@]}"
do
   IFS=$'\n' read -r -a iparraychanged <<< "${iparray[@]}"
done

And what I wanted to receive is to transfer IP's to another array and then read every line from that array and ping it.

UPDATE: I've acknowledged something, it's probably that I want one array to another but without some string, in this case cut "ipHostNumber: " and have remained only IPs.

Thanks in advance, if there's anything missing please let me know.

what I wanted ... ping it. Then do you need arrays at all? Just ping them. — KamilCuk
– KamilCuk, Commented Sep 30, 2021 at 9:54

KamilCuk · Accepted Answer · 2021-09-30 09:55:42Z

1

Why do you need arrays at all? Just read the input and do the work.

while IFS=' ' read -r _ ip; do
   ping -c1 "$ip"
done < "$destlog"

See https://mywiki.wooledge.org/BashFAQ/001 .

Another way is to use xargs and filtering:

awk '{print $2}' "$destlog" | xargs -P0 -n1 ping -c1

answered Sep 30, 2021 at 9:55

KamilCuk

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8 Comments

blazzeq Over a year ago

Well, the first solution works pretty well, thank you, I don't know much from bash. Is there a way to always cut/ignore first line while reading from file?

Jetchisel Over a year ago

awk 'NR > 1' ...

blazzeq Over a year ago

Yes, I've seen awk 'NR > 1' and sed 1d, though I see it's not working in this case with while loop or it's wrongly used: sed 1d | while IFS=' ' read -r _ ip do echo "$ip" done < "$destlog"

Jetchisel Over a year ago

@blazzeq use < <(tail -n+2 "$destlog") instead of < "$destlog"

Jetchisel Over a year ago

@blazzeq take a look at What to do when someone answers your question

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Paul Hodges · Accepted Answer · 2021-09-30 14:01:01Z

0

I prefer KamilCuk's xargs solution, but if you just wanted the array because you plan to reuse it -

$: readarray -t ip < <( sed '1d; s/^.* //' file )

Now it's loaded.

$: declare -p ip
declare -a ip=([0]="127.0.0.2" [1]="127.0.0.3")
$: for addr in "${ip[@]}"; do ping -c 1 "$addr"; done

edited Sep 30, 2021 at 14:01

answered Sep 30, 2021 at 13:54

Paul Hodges

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