Shell Programming and Scripting

I have a problem that I think could (should?) be possible using regular expressions. I've been using regular expressions for some time, so I have some experience with it, but I can't find a way to make this work correctly.

Say I have a long string of different fruits:

and I need the first part of it, up until AT LEAST one of a few keywords occur:

Although grapes and melons are not keywords, they should still be omitted. I only want the text before pears included. The order of all the fruits could be random and as such, the regex should still work.

I tried this, but it doesn't work as I expect:

(.+)(pears|oranges|mangos).*

Instead of matching any of the words, it includes as much as it can until the last keyword it can match - I need it to basically do the opposite.

(By the way, the string could theoretically contain none of the keywords, where I would like to use the entire string instead)

I'm doing this in a perl-script - Any suggestions are welcome

The .* matches absolutely anything, since * is a modifier applied to the last thing.

Got my logic backwards. Thinking.

I'd forget about matching the stuff before, and just find the first instance of pears|mangos|oranges, and get the offset of where it started.

Code:

#!/usr/bin/perl

my $str="apples bananas pears oranges grapes mangos melons";

$str =~ /(pears|oranges|mangos)/g;
print "found verboten fruit at ", pos($str), "\n";
print "match was '", $1, "'\n";
print "things before: ", substr($str, 0, pos($str)-length($1)), "\n";

Be careful with =~ //g matches, because if you re-run it again on the same string, it will return the next match, not the same match.

Yes, that was my though too, but implementing it the way I normally script, would be akward.

I'm new to perl, but this looks really simple! Thanks a lot for the example

Printing only line that contain one of the words until the keyword:

Code:

$ echo "apples bananas pears oranges grapes mangos melons" | perl -ne 'print if s/(pears|oranges|mangos).*//'
apples bananas

Printing every line, but cutting the line from the keyword to the end:

Code:

perl -pe 's/(pears|oranges|mangos).*//'

why use print 3 times?

Code:

perl -ne 'print"$1\n" if /^(.+*(?:pears|oranges|mangos))/' infile

infile contains: apples bananas pears oranges grapes mangos melons

Just as a demonstration of the various features I'm using. I don't play perl golf, I'd never be able to remember what I did