. I don't want to read and then write a line to a temp file because while I may be running this script to modify line 2, someone else may be running it to modify line 1.

Use a database. I'm serious. This requirement is impossible to implement using files. You can use lock-files and the like, but that means you're just queueing up the changes to be done serially instead of parallely. (Not to mention that it's REALLY easy to screw up lockfiles and have everything go to hell in a handbasket mighty quick.)

RDBMS's have facilities for making sure that people cannot write to the same row at the same time. But, people can write to different rows in the same table at the same time. MySQL (and its big brother PostGreSQL) can both do this. (Look for row-level locking vs. table-level locking.)

------
We are the carpenters and bricklayers of the Information Age.

The idea is a little like C++ templates, except not quite so brain-meltingly complicated. -- TheDamian, Exegesis 6

Please remember that I'm crufty and crochety. All opinions are purely mine and all code is untested, unless otherwise specified.

In reply to Re: Modifying lines of text by dragonchild
in thread Modifying lines of text by Anonymous Monk

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