You seem to have misunderstood what i explained. "perl -i" does the same as "sed -i": it creates a temporary second file where it stores the changes and moves this over the original file as the last step.

You gain nothing by using perl (save for a considerably slower speed of execution, because native UNIX commands are way faster).

The point is simple: to edit a file you need to be able to store 2 versions of it.*) There is no way around that. The "-i" options of various tools just blur that fact by hiding this temporary file, but it is still necessary.

If you fear a long execution time for moving the file: don't. It is in fact just a change in the files i-node (which is a few bytes) as long as the temporary file and the original file are on the same filesystem. To execute

Code:

mv /path/to/fileA /path/to/fileB

takes the same time, regardless of the size of this file (as long as they both are on the same filesystem). So set your "TMP" or "TMPDIR" variable accordingly and have enough room on your disk - some 100GB should not really be a problem these times of multi-TB SAN storage fabrics.

I hope this helps.

bakunin

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*) actually this is not completely true, because there is a trick:

Code:

(cat /path/to/file) | sed '<somecommand>' > /path/to/file

This will work for files which are small enough to fit into memory. The downside is, that if anything goes wrong (power loss, reboot, process aborted, ...) your data will be irrevocably destroyed. You sure do not want to use this hack on critical data just to save a few GB of (temporary) diskspace.