Remove all special characters and case from string in bash

regex linux bash shell parsing

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.

regex linux bash shell parsing

Pure BASH 4+ solution:

$ filename='Some_randoM data1-A'$ f=${filename//[^[:alnum:]]/}$ echo "$f"SomerandoMdata1A$ echo "${f,,}"somerandomdata1a

A function for this:

clean() {    local a=${1//[^[:alnum:]]/}    echo "${a,,}"}

Try it:

$ clean "More Data0"moredata0

regex linux bash shell parsing

if you are using mkelement0 and Dan Bliss approach. You can also look into sed + POSIX regular expression.

cat yourfile.txt | sed 's/[^a-zA-Z0-9]//g'

Sed matches all other characters that are not contained within the brackets except letters and numbers and remove them.

CodeHunter

Remove all special characters and case from string in bash

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