This tag is meant for everything that has to do with mathematical operations. So if you want to ask a question about doing calculations in `awk`, or if you have a question about `bc`, this is the right tag to use.

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8
votes
7answers
7k views

Doing simple math on the command line using bash functions: $1 divided by $2 (using bc perhaps)

Sometimes I need to divide one number by another. It would be great if I could just define a bash function for this. So far, I am forced to use expressions like echo 'scale=25;65320/670' | bc but ...
7
votes
4answers
5k views

creating a sequence of numbers, one per line in a file

Is there a way to create out of thin air, a file that is a sequence of numbers, starting at a given number, one per line? something like magic_command start 100 lines 5 > b.txt and then, b.txt ...
1
vote
3answers
710 views

Writing a shell script to take output of an executable and perform some calculation

I am not much familiar with shell script. I want to write a shell script for the following pseudo-code: min=some garbage value for(i=1 to N){ // N and n will be taken as input for the shell script. ...
2
votes
4answers
309 views

Generate lists of page numbers for 2-up duplex printing: 2,3,… and 1,4,…

How can I generate the following increments? 2,3,6,7,10,11,14,15,18,19,22,23,26,27,30,31,34,35,38,39,42,43,46,47,...,135 and ...
3
votes
3answers
10k views

How to calculate values in a shell script?

I run this command in the terminal: grep "bla bla blah" blah* | echo "Blah: $(wc -l) / $(ls | wc -l) * 100" And I get this output: Blah: 44 / 89 * 100 What I expect to see: 49.4 Is there a ...
2
votes
4answers
3k views

Increment number in bash variable string

VERSION="4.0beta12" NEXT_VERSION=????? Writing an automatic release script, I have the current version in a variable $VERSION, and I would like to calculate the next version as $NEXT_VERSION. Rule: ...
3
votes
2answers
379 views

Why does $((40-35)) turn into 5?

What kind of strange shell syntax is hidden behind $((40-35)) and how come it calculates a value? Example: $> echo $((40-35)) 5
6
votes
2answers
701 views

Using bash “double paren” arithmetic expansion, math fails with leading zero

I have a simple script that deals with hours and minutes. If I want to calculate number of minutes since midnight having a string s hh:mm I tried splitting string then doing hh * 60 + mm My problem ...
2
votes
3answers
4k views

grepping a variable and adding 1 to it

I have a variable containing a leading zeroes number, and I want to grep this variable and that same variable plus one. I made several attempts but ran into errors. Here's what I want to do: read var ...
-1
votes
1answer
2k views

Sum of grep results

I need to output the sum of a grep results for a certain time, for now i hard coded the time grep but any help will be very much appreciated, my problem is i cant output the results on the script. If ...
4
votes
2answers
3k views

In bash, how to convert 8 bytes to an unsigned int (64bit LE)?

How can I 'read/interpret' 8 bytes as an unsigned int (Little Endian)? Perhaps there is a Bash-fu magic conversion for this? UPDATE: It seems that something got cross-wired in the interpretation of ...