On 27Dec2016 15:49, JD <jd1008@xxxxxxxxx> 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 $line
done < some_file.txt
for when more than 1 file is involved, it is not so easy ...
Hypothetical (of course, non-working example):
export index=1
while true do;
file_A_line=`read line$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?
It is easy in the shell, too.
Untested:
exec 3<file1
exec 4<file2
while read -r line1 <&3 \
&& read -r line2 <&4
do
... do stuff with $line1 and $line2
done
That's the direct thing. There are other things, depending on what you're
trying to achieve.
Cheers,
Cameron Simpson <cs@xxxxxxxxxx>
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