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I am writing a bash script that needs to parse filenames.

It will need to remove all special characters (including space): "!?.-_ and change all uppercase letters to lowercase. Something like this:

Some_randoM data1-A
More Data0

to:

somerandomdata1a
moredata0

I have seen lots of questions to do this in many different programming languages, but not in bash. Is there a good way to do this?

Answers

cat yourfile.txt | tr -dc '[:alnum:]\n\r' | tr '[:upper:]' '[:lower:]'

The first tr deletes special characters. d means delete, c means complement (invert the character set). So, -dc means delete all characters except those specified. The \n and \r are included to preserve linux or windows style newlines, which I assume you want.

The second one translates uppercase characters to lowercase.