Calculating the sum of two variables in a batch/UNIX single piped line

Question

I would like to execute some basic mathematical calculations in batch/Cygwin, but the solution, described in StackOverflow question: Calculating the sum of two variables in a batch script is using the set /A command for that matter.

This does not suit me, because I'd like to have everything in a pipe (UNIX style, hence the Cygwin).

My idea is the following: I have a list of files, containing an entry. I'd like to show, for all mentioned file, the one line behind that entry.

Therefore I was thinking about following approach:

Find the line where the entry is found: fgrep -n <entry> // this shows the line number together with the entry itself
Only show the line number: fgrep -n <entry> | awk -F ':' '{print $1}'
Add '1' to that number
Take the first amount of entries : head -<new number>
Only take the last line : tail -1

But as I don't know how to add 1 to a number, I am stuck here.

I've already tried using bc (basic calculator) but my Cygwin installation seems not to cover that. As I want to have everything within one piped line, the usage of set /A has not sence.

Does anybody have an idea?
Thanks in advance

You can add BC to your cygwin installation by re-running setup and installing it. — AlG
– AlG, Commented Feb 10, 2017 at 13:11

Dominique · Accepted Answer · 2017-02-10 13:10:53Z

1

Sorry, sorry, I just realised that awk is capable of doing some basic calculations, so by replacing {print $1} by {print $1 + 1} my problem is solved.

answered Feb 10, 2017 at 13:10

Dominique

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Doug Henderson · Accepted Answer · 2017-02-10 17:56:22Z

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Bash has builtin support for declaring variables to be integer and for doing arithmetic on integers. Bash has a help command and you should have both man bash and info bash installed.

answered Feb 10, 2017 at 17:56

Doug Henderson

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