String compare negating in bash doesn't behave as it should be?

Question

I have this little bash script:

readonly imagick_extension=$(cat "${php_configuration_file}" | grep imagick)
echo "Imagick extension grep value: $imagick_extension"
if [ "${imagick_extension}" != "extension=imagick.so" ]; then
        echo "ERROR: Imagick PHP extension is not enabled!"
        exit 1
fi
echo "Imagick PHP extension is enabled."

And the output is:

Imagick extension grep value: extension=imagick.so
ERROR: Imagick PHP extension is not enabled!

How is this possible?

• It says that the variable's value IS extension=imagick.so,

• but it still goes into the if clause where it should only go if it ISN'T extension=imagick.so

Thanks in advance!

Answer 1

The problem here is that you have a PHP configuration file that you created on Windows. As a result its line ending are CR/LF rather than the UNIX standard of LF.

You can prove this by modifying your echo command like this

echo "Imagick extension grep value: < $imagick_extension >"

As confirmed in a comment you see that the output has the last space and > at the beginning of the line, showing that there is indeed an embedded newline character in the value:

 >agick extension grep value: extension=imagick.so

The easy solution is to convert the file to UNIX format:

dos2unix /path/to/php_configuration_file.ini

Or if you don't have the easy dos2unix command, this sed alternative:

sed -i 's/\r//' /path/to/php_configuration_file.ini

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I'm sure there are duplicate answers elsewhere on UNIX&Linux but I can't find them. The closest I've got so far is this related one that gives more detail

• Handling Bash script with CRLF (carriage return) in Linux