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# 1  
Old 09-05-2010
+= operator
im new to bash scripting and im just using online tutorials and trial and error. i wanted to write a script to read numbers from a file and find their sum:



Code:
#!/bin/bash

theSum=0
for line in $(cat numbers.txt)
do
	let "theSum = theSum + $line"
	echo "$line"
done

echo "The sum is $theSum"




when i run this it echoes all the numbers but doesnt give me the correct sum and echo $? returns 0. my console output looks like this:

Code:
$ ./test.sh
")syntax error: invalid arithmetic operator (error token is "
1
")syntax error: invalid arithmetic operator (error token is "
2
")syntax error: invalid arithmetic operator (error token is "
34
")syntax error: invalid arithmetic operator (error token is "
77
89
The sum is 89


im not sure why i am getting those syntax errors. thanks.
Last edited by pludi; 09-06-2010 at 01:57 AM..
# 2  
Old 09-06-2010
BASH doesn't use BASIC's "let" syntax. Try:

Code:
((sum+=line))

Also, "for line in $(cat numbers.txt)" is a two-combo useless use of cat plus useless use of backticks. You can do this much more efficiently and safely as
Code:
while read line
do
        ...
done < numbers.txt

This User Gave Thanks to Corona688 For This Post:
astrolux444
# 3  
Old 09-06-2010
BASH does use "let". Your script runs fine on my env.

Do you try :

Code:
/usr/bin/bash test.sh

# 4  
Old 09-06-2010
The messed up "syntax error" message tells me that that there are probably Microsoft MSDOS carriage return characters in the data. This can arise from creating a text file with say Windows Notepad and copying the file to a unix server without conversion.
 
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