I have a question regarding pattern searching with grep.
I have read tutorials all over the place and pretty much understand how to search for patterns and recurring patterns. I, however, need to search for words which have non-repeating occurances.
My task is to parse a 'permissions' string, ie "ug=rx,o=rw" or "ugo=rwx"
Take the string 'ugo' or 'oug', I basicaly need "grep [ugo][ugo][ugo] but they cannot repeat.
Ie, [ugo]\{3\} but not allow string such as "uuu"
Thanks in advance
Just for clarification:
Your input string is in the format of:
ug=rx,o=rw
ugo=rwx
So, each line can have one or more statements of [ugo] = [rwx]
What are you looking for? Every instance where there is a U&G&O? Instances where there's more than one statement (like the first line)?
Just a little more clarity might help someone with this...
In regular expressions, this allows repetition:
[UGO]
This does not:
(U|G|O)
I don't know the exact syntax in grep, though.
I guess I wasnt't too clear. Lets take an example:
The string in question can be an anagram of 'ugo', ie uog, gou, etc.
I need a regular expression to search for a string like this, where there are only 3 allowed characters, can be in any order, and are not allowed to repeat.
The basic pattern is
u?g?o?(=r?w?x?)?
There is no provision to inline the requirement that there be at least one of ugo and one of rwx for the expression to match; with Perl, you can do lookaheads which accomplish this.
(?=[ugo])u?g?o?(=(?=[rwx]r?w?x?))?
Multiple comma-separated repetitions of this pattern left as an exercise.
Posted while you added your clarification. The above doesn't exactly match your refined requirements. I don't think you can get arbitrary order without repetition without enumerating the possible permutations.
ug?o?|uog?|gu?o?|gou?|og?u?|oug?
since there arent too many permutations, your solution seems to work well era, thx for the help