Linux Bash脚本正则表达式故障

Question

I would like to make a bash script, which should decide about the given strings, if they fulfill the term or not.

The terms are:

• The string's first 3 character must be "le-"
• Between hyphens there can any number of consonant in any arrangement, just one "e" and it cannot contain any vowel.
• Between hyphens there must be something
• The string must not end with hyphen

I made this script:

#!/bin/bash
# Testing regex

while read -r line; do
        if [[ $line =~ ^le((-[^aeiou\W]*e+[^aeiou\W]*)+)$ ]]
        then
           printf "\""$line"\"\t\t\t-> True\n";
        else
           printf "\""$line"\"\t\t\t-> False\n";
        fi
done < <(cat "$@")

It does everything fine, except one thing: It says true no matter how many hyphens are next to each other. For example: It says true for this string "le--le"

I tried this regex expression on websites (like this ) and they worked without this malfunction. All I can think of there must be something difference between the web page and the linux bash. (All I can see on the web page is it runs PHP)

Do you have got any idea, how could I make it work ?

Thank you for your answers!

Answer 1

There's at least one problem with your regex: [^aeiou\\W] - a negated "non-word", means "word" - and it matches any letter , consonants included. Character classes are inclusive, not exclusive. We're better off just listing all the consonants (and for you case, we'll add 'e' and '-' to the set as well).

So try this one : ( edit : using @Laurel's more concise char class)

`(?=^le-)(?!.*--)(?!.*-[^-]*e[^-]*e[^-]*-)[b-hj-np-tv-z-]*[^-]$`

• (?=^le-) starts with 'le-'
• (?!.*--) no double dashes allowed
• (?!.*-[^-]*e[^-]*e[^-]*-) do NOT see two e's between dashes
• [b-hj-np-tv-z-]* - consume consonants, e, and dashes (same as [bcdfghjklmnpqrstlvwze-] )
• [^-]$ last character must be non-dash

Answer 2

sweaver2112 rightly points out that the \\W is causing you problems, but fails to provide a working example of a bash test regex that does what you ask (at least, i couldn't get it to work).

this seems to do it (adapting Laurel 's consonant regex):

[[ "$line" =~ ^le(-[b-df-hj-np-tv-z]*e[b-df-hj-np-tv-z]*)+$ ]]

it matches (eg):

le-e
le-e-le
le-e-e-e-e-e

and more generally:

le-([[:consonant:]]*e[[:consonant:]]*)+

and doesn't match (eg):

le-
le--le
le-lea-le

also, you can write it more cleanly this way:

c='[b-df-hj-np-tv-z]'
[[ "$line" =~ ^le(-$c*e$c*)+$ ]]