On 21Nov2005 00:19, Dave Mitchell <davem@xxxxxxxxx> wrote: | On Mon, Nov 21, 2005 at 11:06:02AM +1100, Cameron Simpson wrote: | > Bsed is a wrapper for sed. It takes pretty well the same arguments as sed, | > but edits files in place. I frequently use it for batch edits; it's very | > handy. Example: | > | > bsed '4s/that/that/' filename.txt | > | > Replace "this" with "that" on line 4. It essentially does all the redirection | > of the first sed with error handling, temp files and such. | | Note that perl can do a similar edit-in-place, eg | | perl -ipe 's/this/that/' *.txt But screws over the file attributes. BTW, you really mean this: perl -i -pe 's/this/that/' *.txt But watch: [~]zoob*> echo hello >foo [~]zoob*> ls -ldi foo 6210174 -rw-r--r-- 1 cameron cameron 6 Nov 21 11:23 foo [~]zoob*> perl -i -pe 's/hell/jell/' foo [~]zoob*> ls -ldi foo 1350276 -rw-r--r-- 1 cameron cameron 6 Nov 21 11:25 foo See? A new file. Had it had hard links, they would now be broken. And again: [~]zoob*1> ls -ldi foo bar 1350272 lrwxrwxrwx 1 cameron cameron 3 Nov 21 11:27 bar -> foo 1350276 -rw-r--r-- 1 cameron cameron 6 Nov 21 11:25 foo [~]zoob*> perl -i -pe 's/jell/hell/' bar [~]zoob*> ls -ldi foo bar 1350272 -rw-r--r-- 1 cameron cameron 6 Nov 21 11:28 bar 1350276 -rw-r--r-- 1 cameron cameron 6 Nov 21 11:25 foo Symlink gone, replaced with a new file! (Same inode, freed by the file remove). So, perl-i does damage. For this reason I NEVER use it. Besides, for many things Perl is overkill. I tend to use the smallest tool that will succinctly do the job. So: tr, sed, awk perl/python in that order typically. Or of course some combination. Cheers, -- Cameron Simpson <cs@xxxxxxxxxx> DoD#743 http://www.cskk.ezoshosting.com/cs/ I'd climb a mountain for a llama. - _The Shadow_
