Save multiple variables from bash script to text file

Question

I have a simple bash script I have written to count the number of lines in a collection of text files, and I store each number of lines as a variable using a for loop. I would like to print each variable to the same text file, so that I may access all the line counts at once, from the same file.

My code is:

for f in *Daily.txt; do
    lines=$(cat $f | wc -l);
    lines=$(($num_lines -1));
    echo $lines > /destdrive/linesTally2014.txt;
done

When I run this, the only output I receive is of the final file, not all the other files.

If anyone could help me with this I would really appreciate it. I am new to bash scripting, so please excuse this novice question.

lines=$(( $(wc -l < "$f") - 1)) would be the proper way to get that value in one line. — chepner
– chepner, Commented Oct 29, 2015 at 16:07
@chepner: I think it is more a question that lines=$(($num_lines - 1)) is a typo for lines=$(($lines - 1)). But there is a problem with name consistency. — Jonathan Leffler
– Jonathan Leffler, Commented Oct 29, 2015 at 16:09

Jonathan Leffler · Accepted Answer · 2015-10-29 16:18:22Z

2

You create the file on each iteration. Move the I/O redirection after the done. Use:

for f in *Daily.txt
do
    echo $(( $(wc -l < $f) - 1))
done > /destdrive/linesTally2014.txt

This avoids the variable; if you have a need for it, you can use a fixed version of the original code (use $lines throughout, instead of using $num_lines once). Note that the code in the question has a UUoC (Useless Use of cat) that this version avoids.

edited Oct 29, 2015 at 16:18

answered Oct 29, 2015 at 16:07

Jonathan Leffler

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Comments

Walter A · Accepted Answer · 2015-10-29 16:21:27Z

1

You can avoid the loop with

wc -l *Daily.txt | awk '{ print $1 }' > /destdrive/linesTally2014.txt

or (when you want 1 less)

wc -l *Daily.txt | awk '{ print $1 -1 }' > /destdrive/linesTally2014.txt

answered Oct 29, 2015 at 16:21

Walter A

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Comments

miken32 · Accepted Answer · 2015-10-29 16:23:14Z

0

The above suggestions are probably better, but the problem you're having with your script is your use of the > for redirection, which overwrites the file. Use >> and it will append to the file.

echo $lines >> /destdrive/linesTally2014.txt

answered Oct 29, 2015 at 16:23

miken32

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1 Comment

miken32 Over a year ago

No problem and welcome to SO; if you found any of the answers useful, upvote them, and mark the most helpful one as "accepted" by clicking the checkmark.

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