Escape dots and asterisks in command line variable output string

Question

I have a command that sets an environment variable from a command like this:

BLACKLIST=$(python tools.py gen-blacklist)

Which results in a string that contains dots * and asterisks *, like this:

LISTEN,UNLISTEN,NOTIFY,SHOW,REFRESH,pg_notify,.*remove,.*delete,.*update,.*create,.*insert

I want to be able to escape all the dots and asterisks in the string, this is what I have tried:

TEMP=$(python tools.py gen-blacklist) && BLACKLIST=$(echo ${TEMP/.\*/\\.\\*}) && echo $BLACKLIST

but it only replaces at the first occurence.

LISTEN,UNLISTEN,NOTIFY,SHOW,REFRESH,pg_notify,\.\*remove,.*delete,.*update,.*create,.*insert

How do I escape for all occurences of * and .?

Answer 1

Smells like an xy problem, but regardless...

From parameter expansion, this is what the manual has to say on ${parameter/pattern/string}-style expansions -

If pattern begins with ‘/’, all matches of pattern are replaced with string. Normally only the first match is replaced

Therefore ${TEMP/.\*/\\.\\*} needs to change to ${TEMP//.\*/\\.\\*} (notice the additional / immediately after TEMP).

This yields LISTEN,UNLISTEN,NOTIFY,SHOW,REFRESH,pg_notify,\.\*remove,\.\*delete,\.\*update,\.\*create,\.\*insert

Answer 2

Quote more (™) ....

Try:

TEMP=$(python tools.py gen-blacklist) &&
echo "$TEMP"

If you really need the dots and asterisks escaped, use (in bash):

TEMP=$(python tools.py gen-blacklist) &&
BLACKLIST=${TEMP//\.\*/\\.\\*} &&
echo "$BLACKLIST"