removing all whitespace but newlines

blacksmith has asked for the wisdom of the Perl Monks concerning the following question:

Okay I have resolved my initial problem. Actually resolved it because writing this gave me an idea to a different approach to resolution. This is what I had going on. I have a .txt file that I am trying to upload to a mainframe for processing. Each record in the file should only be 12 characters long. But, the file that was sent to me to upload has a large amount of whitespace (this includes one \n) trailing the 12 digit record. The FTP step in the mainframe job rejects the file since it is looking for a 12 digit record. So here is what I am trying to do. I am trying to find a way to delete to "spaces" and leave the newline. For some reason everytime I negate \n it doesn't work correctly. Or, I should say the way I want it to work. Perl doesn't lie. I always works correctly. I just don't always script correctly. I went about fixing this issue by using sprintf. I felt this would be more acurate since the record length must be 12, no more, no less. But, I am still curious. How do you delete all whitespace but the newline?
blacksmith

Comment on removing all whitespace but newlines

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Re: removing all whitespace but newlines by thelenm (Vicar) on Jan 28, 2003 at 19:29 UTC
Perhaps something like this, which will remove all whitespace except for newlines, if your line is in `$line`. `$line =~ s/[^\S\n]+//g;` [download] If you need to remove just trailing whitespace, change it to this: `$line =~ s/[^\S\n]+$//g;` [download] Update: I should point out explicitly that that's a capital S inside the character class... the character class matches anything that's non-non-whitespace (i.e., whitespace) and non-newline. -- Mike `-- just,my${.02}`	[reply] [d/l] [select]
Re: removing all whitespace but newlines by Abigail-II (Bishop) on Jan 28, 2003 at 22:02 UTC
One way of doing so would be: `perl -wi -lpe 's/[[:space:]]+//g' file` [download] Note the use of `[:space:]`, the POSIX character class that includes all the whitespace characters. `\s` will not do, as that does not include the vertical tab character. Newlines won't be removed by the code above, as they are chopped off when reading a line, and added back on when printing it. It's the `-l` that will do this. Abigail	[reply] [d/l] [select]
Re: removing all whitespace but newlines by ibanix (Hermit) on Jan 28, 2003 at 19:34 UTC
How do you delete all whitespace but the newline? A simple and probally inefficent way to do it, assuming you're processing one line at a time: `$line =~ s/\s+//g; # But this replaces \n too, so add it back on the end $line . "\n";` [download] Cheers, ibanix `$ echo '$0 & $0 &' > foo; chmod a+x foo; foo;`	[reply] [d/l] [select]
Re: (nrd) removing all whitespace but newlines by newrisedesigns (Curate) on Jan 28, 2003 at 19:31 UTC
Does each field have only A-Z0-9 characters? If so, `$_ =~ /((\w{12})\n)/;` $1 = the 12 digit field plus the newline, while $2 = the 12 digit field without. If you need other characters, you could use `$_ =~ /(([A-Za-z0-9\.\+\-]{12})\n)/;` To get alphanumerics and '.', '+', and '-'. John J Reiser newrisedesigns.com	[reply] [d/l] [select]
Re: removing all whitespace but newlines by Gilimanjaro (Hermit) on Jan 28, 2003 at 20:17 UTC
Or using my newlyfound perlrun knowledge: When there never are spaces in the end of the 12 characters, and you're sure all lines do contain 12 non-space characters: `perl -i -lpe 's/\s+^//' myfile` [download] Or the foolproof way: `perl -lne '/^.{1,12}/; printf "%-12s\n",$&' myfile` [download] I think I just started playing perlgolf...	[reply] [d/l] [select]
Re: removing all whitespace but newlines by integral (Hermit) on Jan 28, 2003 at 19:36 UTC
One solution, assuming that the twelve chars are at the start of each line: `local $\ = "\n"; while(<>) { print substr $_, 0, 12 }` [download] -- integral, resident of freenode's #perl	[reply] [d/l]
Re: removing all whitespace but newlines by blacksmith (Hermit) on Jan 28, 2003 at 22:21 UTC
Thanks fellow monks. It's been a great experience seeing some of the different ideas. Really helped stimulate my mind to learn new things!! blacksmith.	[reply]