Shell Programming and Scripting

True. To be honest i had a "comprehension error" and thought OP wanted to change character 8-15 instead of 7-14 - my fault entirely. As you say this can easily be corrected. Of course the ksh-script was based on this faulty assumption too, which explains its wrong output. It could also be easily corrected.

True - it was meant as a fallback solution in case sed wouldn't do the job and written not to be as fast as possible, but to be as easy to understand as possible.

Thank you for taking the time to compare the different solutions, though, it justs points out my mantra: use sed if you can and awk, if you must for maximum performance.

bakunin

@rikxik:
while loops in shell are almost always slower than tools like awk/sed. the "looping" construct of awk/sed is already "inside" the language. In shell, you have to "explicitly" code the loop.

@ghostdog74

Correct - looping is always slow. One more thing, I believe sed (being the stream editor) operates on streams with newline differentiating lines - so it is not exactly "looping" - I suppose thats why sed aces awk. I'm not very sure about the internal mechanism used by awk.