Bash string comparison gives wrong value-CodePudding

I have following bash script which is supposed to download the current Wikipedia ZIM file if the file size differs:

#!/bin/bash

wikipedia_current_filesize=$(stat -c %s wikipedia.zim)
wikipedia_download_filesize=$(curl -s -L -I https://download.kiwix.org/zim/wikipedia_de_all_maxi.zim | gawk -v IGNORECASE=1 '/^Content-Length/ { print $2 }')

echo "Wikipedia filesize [current / download]:"
echo "$wikipedia_current_filesize / $wikipedia_download_filesize"

if [ "$wikipedia_current_filesize" != "$wikipedia_download_filesize" ]
then
  echo "Downloading newer version of Wikipedia..."
else
  echo "No new version for Wikipedia available."
fi

The output is:

Wikipedia filesize [current / download]:
38095908569 / 38095908569
Downloading newer version of Wikipedia...

The numbers are exactly the same. Why do I still get into the if and not into the else branch here? Am I comparing strings the wrong way here? Is there maybe a more meaningful way, e.g. by comparing integers instead of strings?

CodePudding user response：

HTTP responses use \r\n line endings.

gawk's default record separator is newline, which leaves the carriage return as a plain character in the last field. It can remove the trailing carriage return.

wikipedia_download_filesize=$(
    curl -s -L -I https://download.kiwix.org/zim/wikipedia_de_all_maxi.zim \
    | gawk -v IGNORECASE=1 '/^Content-Length/ { print gensub(/\r$/, "", 1, $2) }'
)

Or, more awk-ishly

wikipedia_download_filesize=$(
    curl -s -L -I https://download.kiwix.org/zim/wikipedia_de_all_maxi.zim \
    | gawk -v IGNORECASE=1 -v RS='\r\n' '/^Content-Length/ { print $2 }'
)