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Top Forums Shell Programming and Scripting how to do decimal arithmetic in shell script Post 302686293 by Don Cragun on Tuesday 14th of August 2012 08:45:16 AM
Old 08-14-2012
Code:
$sum=0; for i in `cat b22`
do
sum=`echo "$sum + $i" | bc`
done; echo $sum;

would have worked if you had changed $sum=0 on the first line to sum=0
I assume that the variable sum was not set when you started so the first command turned into =0 when $sum expanded to an empty string.

However, it is pretty inefficient to invoke bc for each value you want to add. A much simpler way would be to use:
Code:
awk ' {	for (i=1; i<= NF; i++) sum+=$i }
END {print sum}' b22

which only invokes awk once instead of invoking bc 265 times. (Note that you have 265 values in b22; not 256.)
This User Gave Thanks to Don Cragun For This Post:
 

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ATF-SH(1)						    BSD General Commands Manual 						 ATF-SH(1)

NAME
atf-sh [-s shell] -- interpreter for shell-based test programs SYNOPSIS
atf-sh script DESCRIPTION
atf-sh is an interpreter that runs the test program given in script after loading the atf-sh(3) library. atf-sh is not a real interpreter though: it is just a wrapper around the system-wide shell defined by ATF_SHELL. atf-sh executes the inter- preter, loads the atf-sh(3) library and then runs the script. You must consider atf-sh to be a POSIX shell by default and thus should not use any non-standard extensions. The following options are available: -s shell Specifies the shell to use instead of the value provided by ATF_SHELL. ENVIRONMENT
ATF_LIBEXECDIR Overrides the builtin directory where atf-sh is located. Should not be overridden other than for testing purposes. ATF_PKGDATADIR Overrides the builtin directory where libatf-sh.subr is located. Should not be overridden other than for testing purposes. ATF_SHELL Path to the system shell to be used in the generated scripts. Scripts must not rely on this variable being set to select a specific interpreter. EXAMPLES
Scripts using atf-sh(3) should start with: #! /usr/bin/env atf-sh Alternatively, if you want to explicitly choose a shell interpreter, you cannot rely on env(1) to find atf-sh. Instead, you have to hardcode the path to atf-sh in the script and then use the -s option afterwards as a single parameter: #! /path/to/bin/atf-sh -s/bin/bash ENVIRONMENT
ATF_SHELL Path to the system shell to be used in the generated scripts. SEE ALSO
atf-sh(3) BSD
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