Re: Shell question

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On 12/27/2016 11:49 PM, JD wrote:
Reading lines from 2 files in such a way that each iteration
lets me read the next line from each file so that the items
read from each file are in sync as far as line number is concerned.
Is this "doable"?

For a single file, indexing to next line is automatic, visa vis
while read line; do
echo $line
done < some_file.txt

for when more than 1 file is involved, it is not so easy ...

JD,

If using the bash, you could introduce file descriptors for each file you are reading from ( set the fie descriptor by using the exec command) and then read using the -u option for each file.

Kind regards

Joachim Backes



Hypothetical (of course, non-working example):

export index=1
while true do;
file_A_line=`read line$index`  # Read from file A
file_B_line=`read line$index`  # read from file B
[ x$file_A_line = x -o x$file_B_line = x ] && break
<do something withfile_A_line and file_B_line>
index=`expr $index + 1`
done

So how can the reading from 2 files be accomplished and keep the index
to next line in sync?

I know it is a no brainer with a C program.

Thanx.

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--

Fedora release 25 (Twenty Five)
Kernel-4.8.15-300.fc25.x86_64


Joachim Backes <joachim.backes@xxxxxxxxxxxxxx>
https://www-user.rhrk.uni-kl.de/~backes/
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