Re: [OT] Scripting question: the length limit of a list?
Richard Lyons <email@example.com>:
> On Thu, Nov 01, 2007 at 01:49:03PM -0700, Mike Bird wrote:
> > On Thursday 01 November 2007 13:07, Wei Chen wrote:
> > > I would like to write a bash script like the following one:
> > >
> > > for i in `some program that outputs a word list`
> > > do
> > > echo $i
> > > done
> > >
> > > where the word list can be very very long. I wonder what is the upper bound
> > > limit of the length of word lists in "for" loop of a bash script, or
> > > does it only
> > > depend on the hardware (say, RAM)? Thank you in advance.
> > Assuming that the words are output one per line, something
> > like the following can handle lists of any size:
> > some program | while read i; do echo $i; done
> A wild thought, but if you want to count the words in the output can you
> not pipe it to wc? I haven't tried, this is just a thought...
Not wild at all. Most *ix apps (of the commandline variety, at least)
are designed to expect input on their stdin if it's there. wc's no
exception. "some_program | wc -l" will give you the number of lines
of output produced by some_program. Exercise for you: play around
some_program | grep -c "some_string"
which does the same thing, but only on lines you want to know about.
Any technology distinguishable from magic is insufficiently advanced.
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