CODEWITHSUNDEEP
linuxxargs
yegor256
yegor256

Reputation: 105133

How to stop xargs on first error?

I have an pages.txt file with 100 URLs inside. I want to check them one by one and fail on the first problem. This is what I'm doing:

cat pages.txt | xargs -n 1 curl --silent \
  --output /dev/null --write-out '%{url_effective}: %{http_code}\n'; echo $?

Exit code is 1, but I see it only when the entire file is done. How to stop earlier, on the first problem?

Upvotes: 56

Views: 19970

Answers (2)

davrieb
davrieb

Reputation: 579

I haven't found a way to do what you ask for with xargs, but a loop with read might be what you are looking for.

while read URL; do
  curl --silent \
    --output /dev/null --write-out '%{url_effective}: %{http_code}\n' $URL;
  RET=$?;
  echo $RET;
  if [ $RET -ne 0 ]; then break; fi
done < pages.txt

Upvotes: 3

whoan
whoan

Reputation: 8531

General method

xargs -n 1 sh -c '<your_command> $0 || exit 255' < input

Specific case

xargs -n 1 sh -c 'curl --silent --output /dev/null \
    --write-out "%{url_effective}: %{http_code}\n" $0 || exit 255' < pages.txt

Explanation

For every URL in pages.txt, executes sh -c 'curl ... $0 || exit 255' one by one (-n 1) forcing to exit with 255 if the command fails.

From man xargs:

If any invocation of the command exits with a status of 255, xargs will stop immediately without reading any further input. An error message is issued on stderr when this happens.

Upvotes: 85

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