Arithmetic operation in variable


Login or Register for Dates, Times and to Reply

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Arithmetic operation in variable
# 1  
Arithmetic operation in variable

Hi,

Here is the script i try to perform arithmetic operation in two variables .

Code:
git branch -r | while read brname ; do
REV_COMMITS=`git rev-list --count $brname`
echo "$brname has $REV_COMMITS"
(( TOTAL = TOTAL + REV_COMMITS ))
echo "in loop" $TOTAL
done
echo "total is " $TOTAL

Output:
Quote:
x has 13326
in loop 13326
y has 17459
in loop 30785
z has 1170
in loop 31955
total is 0
In side the loop, i get correct value of variable TOTAL.
How to get correct TOTAL outside while loop ?
# 2  
This question pops up an awful lot.

When you run shell commands in a pipe, they exist inside a different shell. This shell sums up the value perfectly and quits - leaving you in your original shell where the value was never changed.

Which end of the pipe is 'your' shell can vary from shell to shell. In KSH, you'd have gotten the total; I suspect you're running bash.

There's a few ways to deal with this and make it work in both.

Stuffing the entire program into the subshell with ( ) grouping braces:

Code:
git branch -r | (
        while read something
        do
                ...
        done 

        echo "total is $total"
)

Here-doc:

Code:
while read something
do
...
done <<EOF
$(git branch -r)
EOF

You could also use a temp file.
This User Gave Thanks to Corona688 For This Post:
# 3  
Please don't ask technical questions in private messages.

Subshells
# 4  
You could also have the loop as:-

Code:
while read something
do
   whatever
done < <(git branch -r)

Note that space between the two < characters.

I hope that this helps,
Robin

Last edited by rbatte1; 09-07-2016 at 07:04 AM.. Reason: Added note.
Login or Register for Dates, Times and to Reply

Previous Thread | Next Thread
Thread Tools Search this Thread
Search this Thread:
Advanced Search

Test Your Knowledge in Computers #98
Difficulty: Easy
Unix was the first operating system that was written in a high-level programming language (C Language).
True or False?

10 More Discussions You Might Find Interesting

1. How to Post in the The UNIX and Linux Forums

How to get defined precision after arithmetic operation using syncsort?

I have to do some arithmetic operation on Field 8 which is calculated by Field 9/Field 7 Suppose i have data like : 0800123456|JAN|2017|JAN|2018|0800123456|0|0.0000|0.00| 0800234567|JAN|2017|JAN|2018|0800234567|4|2.5812|10.32| 0800666666|JAN|2017|JAN|2018|0800666666|2|1.7255|3.45|... (0 Replies)
Discussion started by: pumrao
0 Replies

2. Shell Programming and Scripting

Using awk to do arithmetic operation

Hi, I've this following text file FileVersion = 1.03 Filetype = meteo_on_curvilinear_grid TIME = 0 hours since 2016-10-03 12:00:00 +00:00 -6.855 -6.828 -6.801 -6.774 -6.747 -6.719 -6.691 -6.663 -6.634 -6.606 -6.577 -6.548 -6.519 -6.489 TIME = 0 hours since... (2 Replies)
Discussion started by: xisan
2 Replies

3. UNIX for Dummies Questions & Answers

Basic arithmetic operation with awk?

input: Name|Operation rec_10|1+2+2- Output: rec_10|1 Basically I am trying to calculate the result of "the path" in $3 where the operators follow the number and not preceding them like we normally do: rec_10: +1+2-2=1 But I realise (I am sure there is a good reason for that) that awk... (7 Replies)
Discussion started by: beca123456
7 Replies

4. Shell Programming and Scripting

floating point arithmetic operation error

I am writing a script in zsh shell, it fetchs a number from a file using the awk command, store it as a variable, which in my case is a small number 0.62000. I want to change this number by multiplying it by 1000 to become 620.0 using the command in the script var2=$((var1*1000)) trouble is... (2 Replies)
Discussion started by: piynik
2 Replies

5. Shell Programming and Scripting

Arithmetic operation between columns using loop variable

Hi I have a file with 3 columns. say, infile: 1 50 68 34 3 23 23 4 56 ------- ------- I want to generate n files from this file using a loop so that 1st column in output file is (column1 of infile/(2*n+2.561)) I am doing like this: for ((i=1; i<=3; i++)) do a=`echo... (3 Replies)
Discussion started by: Surabhi_so_mh
3 Replies

6. Shell Programming and Scripting

Arithmetic operation with awk

I have output like following in a file usmtnz-dinfsi19 72 71 38 1199 1199 0.8 19:23:58 usmtnz-dinfsi19 72 71 38 1199 1199 0.8 19:24:04 (9 Replies)
Discussion started by: fugitive
9 Replies

7. Shell Programming and Scripting

How to perform arithmetic operation on date

Hi all, I would appreciate if anyone knows how to perform adding to date. As for normal date, i can easily plus with any number. But when it comes to month end say for example 28 Jun, i need to perform a plus with number 3, it will not return 1 Jul. Thanks in advance for your help. (4 Replies)
Discussion started by: agathaeleanor
4 Replies

8. UNIX for Dummies Questions & Answers

arithmetic operation on two columns

Hi, All, I have a file, its content is as follows: 100 150 120 135 140 170 I want to insert a column, its content is determined by the difference between the two values in the same line, if the difference is less than 20, the new value is 1, otherwise is 0. after the operation, the... (1 Reply)
Discussion started by: Jenny.palmy
1 Replies

9. Shell Programming and Scripting

Help with arithmetic operation

I am using egrep to extract numbers from a file and storing them as variables in a script. But I am not able to do any arithmetic operations on the variables using "expr" because it stores them as char and not integers. Here is my code and the error I get. Any help will be appreciated. #!/bin/sh... (3 Replies)
Discussion started by: emjayshaikh
3 Replies

10. Shell Programming and Scripting

Simple arithmetic operation

I have no idea why I can't get this to work, if anybody can help i would appreciate it. #!/bin/bash x=`cat counter.txt | wc -l` y= '$x / 7' printf "%d People have visited this page" $y :confused: (2 Replies)
Discussion started by: paladyn_2002
2 Replies

Featured Tech Videos