Visit Our UNIX and Linux User Community


Syntax error in subtraction in Bash


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Syntax error in subtraction in Bash
# 1  
Old 10-21-2019
Syntax error in subtraction in Bash

I am sharing a code snippet.
Code:
for (( i=0; i<=$(( $count -1 )); i++ ))
do

	first=${barr2[$i]}
	search=${barr1[$i]}
        echo $first
	echo "loop begins"
	for (( j=0; j<=5000; j++ ))
	do
		if [[ ${harr1[j]} == $search ]]; then
			echo $j
			break;
		fi

	done
	second=${harr2[$j]}	
	echo $second
	
	diff=$((second-first))
	echo "diff" 
	echo $diff
done

I am getting a syntax error in line of subtraction that says something like:
syntax error: invalid arithmetic operator (error token is ".0985146")

This is the line that gives error.
Code:
	diff=$((second-first))

Appreciate your help.
# 2  
Old 10-21-2019
I am assuming you are using bash or perhaps a POSIX shell like dash.
Your error is telling you that it is not possible to do such a task as these shells have INTEGER arithmetic only.

If you need floating/fixed point arithmetic then you will have to do workarounds using, bc, dc, python, perl, awk or any other methods that are capable of such mechanisms.

(Just an observation, you have both, ${barr1[$i]} and also ${harr1[j]} are these correct?)

EDIT:
Note the second one should have ${harr1[$j]}

An example longhand using INTEGER arithmetic and FIXED point, OSX 10.14.6, default bash terminal:
Code:
Last login: Mon Oct 21 18:25:40 on ttys000
AMIGA:amiga~> x=.098765
AMIGA:amiga~> y=10.3
AMIGA:amiga~> x=$( printf "%.f" ${x}e+12 )
AMIGA:amiga~> y=$( printf "%.f" ${y}e+12 )
AMIGA:amiga~> printf "%.12f\n" $(( y - x ))e-12
10.201235000000
AMIGA:amiga~> _


Last edited by wisecracker; 10-21-2019 at 03:50 PM.. Reason: See EDIT:
These 3 Users Gave Thanks to wisecracker For This Post:
# 3  
Old 10-21-2019
Nice wisecracker. This method would rap up into a fun little bash sum function:

Code:
function sum
{
   local word exp var

   [[ "$1" = *= ]] && var="-v ${1%=}" && shift

   for word in "$@"
   do
       case "$word" in
          [0-9.]*|-[0-9.]*|+|-)
              printf -v ans "%.f" "${word}e+12" 2>/dev/null || ans=$word
              exp="$exp $ans" ;;
          *) echo "sum: $word operator not supported" >&2 ; exit 1 ;;
       esac
   done
   printf $var "%.8f\n" $(( $exp ))e-12
}

sum val= 3.58047 - .68 + .858 + -1.2
echo $val

These 2 Users Gave Thanks to Chubler_XL For This Post:

Previous Thread | Next Thread
Test Your Knowledge in Computers #824
Difficulty: Medium
HTML 5 specifies scripting application programming interfaces (APIs) that can be used with JavaScript.
True or False?

10 More Discussions You Might Find Interesting

1. BSD

Keep getting error "-bash: ./.profile_z2: line 52: syntax error: unexpected end of file"

#!/bin/bash #-------------------------------------------------------- # Setup prompt # Author Zeeshan Mirza # Data: 06-08-2017 #-------------------------------------------------------- if then . ./.profile_custom_pre fi umask 022 set -o vi export EDITOR=vi export VISUAL=vi... (3 Replies)
Discussion started by: getzeeshan
3 Replies

2. Shell Programming and Scripting

Bash calling a few functions syntax error

In the bash function below if the user selets "y" then the menu function is called and if they select "n" the move function is called. That all seems to work, my question is after the files are moved an echo, line in bold is displayed and another function called backup is called. I am getting a... (1 Reply)
Discussion started by: cmccabe
1 Replies

3. Shell Programming and Scripting

Bash function using variable in it syntax error

The below bash function uses multiple variables CODING, SAMPLE, SURVEY, andvariant in it. The user selects the cap function and details are displayed on the screen using the $SURVEY variable, the directory is changed to $SAMPLE and the samples.txt is opened so the user can select the sample to... (6 Replies)
Discussion started by: cmccabe
6 Replies

4. Shell Programming and Scripting

Basic Bash algorithm with sum/subtraction

Hi all, i'm making some test on a data file. Imagine i have two columns inside it : 80377,20 80377,20 80379,19 80378,20 80380,20 80382,20 80381,21 Just to understand how can it works, imagine to subtract 100 to the number in the first column when the other one in the second... (4 Replies)
Discussion started by: Board27
4 Replies

5. Shell Programming and Scripting

-bash: syntax error near unexpected token `('

// AIX 6.1 I am getting a syntax error below. Please advise what to be corrected. :confused: runmqsc CERN.$(echo `hostname` | cut -d'.' -f1 | tr '' '').$(echo $environment | tr '' '') <<! | egrep -i '(FROM.NC.APPLIANCE)' | sort -u |awk '{print $2}' | cut -d '(' -f2 | cut -d ')' -f1 |... (1 Reply)
Discussion started by: Daniel Gate
1 Replies

6. Shell Programming and Scripting

Trying to pass a password: bash: syntax error near unexpected token `('

howdy, so I'm make a plugin work for Nagios, and the commandline is: /usr/lib/nagios/plugins/check_mssql -H MySQLServerName -u MySqlAccountName -p MyPassword(#XXXXX -d MyDatabaseName it is barfing with: bash: syntax error near unexpected token `(' Thoughts? Do I have to wrap something... (2 Replies)
Discussion started by: rgouette
2 Replies

7. Shell Programming and Scripting

Bash syntax error

while read line do mkdir $line scp -r Docking_results/docking_$line.pdb $line/ cd /$line/ set a=`grep ENDMDL docking_'$line'.pdb | wc -l` set b=`expr $a - 2` csplit -k -s -n 3 -f docking_'$line'. docking'$line'.pdb '/^ENDMDL/+1' '{'$b'}' foreach f (... (4 Replies)
Discussion started by: chrisjorg
4 Replies

8. Shell Programming and Scripting

bash syntax error: command not found

I am trying to create a shell that asks the user to enter their name, and compare it to my own by saying we have the same name or saying my name and that they have a nice name too. Here is my script... #!/bin/bash-x echo "Enter your name". read name if then echo "My name is Adam too"... (1 Reply)
Discussion started by: amaxey45
1 Replies

9. Shell Programming and Scripting

subtraction in bash arrays

hi i am using bash shell to perform some subraction. here is what i have: i have a while loop and am using i as a counter. diff= `expr ${ARRAY1} - ${ARRAY2}` for example array1 has -0.7145 and array2 has -0.7041. when i try the above command, i get expr: non-numeric argument. any... (6 Replies)
Discussion started by: npatwardhan
6 Replies

10. Shell Programming and Scripting

BASH Script syntax error

I'm trying to write a simple script that takes all the .tar.gz files in a directory and verifies them by using the gzip -tv command: for zip in *.tar.gz do gzip -tv $zip if ; then #Check return code from tar echo "File ${zip} verified OK." exit... (4 Replies)
Discussion started by: kelldan
4 Replies

Featured Tech Videos