I'm trying to convert this working bash script into an Ash script,
read -p "Username:" _username
if ! [[ "$_username" =~ [^a-zA-Z0-9] ]]; then
echo "Valid"
else
echo "INVALID"
fi
However, Ash does not recognize the "=~" character.
How can I do this?
Also, is there a good reference guide, so I don't need to post all my questions here? I can't find anything!
The bash shell provides lots of extensions above and beyond what the POSIX standards require. The ash shell doesn't provide nearly as many extensions. If you use the standard as your shell programming guide, you should get by OK. A straight translation (getting rid of bash extensions) for your script would be:
printf "Username:"
read _username
if [ "$_username" = "${_username%[^a-zA-Z0-9]*}" ]
then echo "Valid"
else echo "INVALID"
fi
If your system allows alphanumeric characters other than characters in the Portable Filename Character Set in user names, you might want:
printf "Username:"
read _username
if [ "$_username" = "${_username%[^[:album:]]*}" ]
then echo "Valid"
else echo "INVALID"
fi
Hi.
This may be useful ... cheers, drl
checkbashisms | Free Development software downloads at SourceForge.net
I'd like to add that in any case, letting variable names start with underscores is a problematic practice, even if it is allowed. Consider:
_foo="bar"
echo $_foo
_="bar"
echo $_
I hope this helps.
bakunin
printf "Username:"; read _username
if [[ "$_username" != *[!a-zA-Z0-9]* ]]; then
echo "Valid"
else
echo "INVALID"
fi
A case statement will work in any Bourne type shell. This also makes it easy to test for an empty variable..
printf "Username: "
read _username
case $_username in
(*[![:alnum:]]*|"")
echo "invalid" ;;
(*)
echo "valid"
esac
Note that will also allow letters with accents like � and �
To exclude those, you could use (*[!a-zA-Z0-9]*|"") but that may not work properly because of a locale collation order...
--
Also note hat the proper negation character with character sets used in patterns is ! not ^ (even though it probably will work too)