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Shell Programming and Scripting

arrays and substitutions

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# 1  
Old 01-06-2011
arrays and substitutions
I am working on a bash script and ran around this issue. here's the code :

Code:
#!/bin/bash

string="\"bin\" \"barn\" \"bin, barn /\""
array=($string)
echo -e "\nMethod 1\narray[2] is ---> ${array[2]}"
echo -e "array=($string)"

array=("bin" "barn" "bin, barn /")
echo -e "\nMethod 2\narray[2] is ---> ${array[2]}"
echo -e 'array=("bin" "barn" "bin, barn /")'"\n"
exit

I would suspect that the output of array[2] should be identical for both methods but they are not. Here is the output :
Quote:
Method 1
array[2] is ---> "bin,
array=("bin" "barn" "bin, barn /")

Method 2
array[2] is ---> bin, barn /
array=("bin" "barn" "bin, barn /")
Thanks for your feedback.
# 2  
Old 01-06-2011
It's to do with the order the shell performs expansions.

word splitting is done after variable expansion.

You could eval the line to get a 2nd bite of the cherry
Code:
eval array=($string)

Or change IFS (I like this solution because it looks a lot neater and avoids possible hyjacks):
Code:
string="bin|barn|bin, barn"
IFS="|" array=($string)

This User Gave Thanks to Chubler_XL For This Post:
titou_dude
# 3  
Old 01-07-2011
Here is another approach to arrays
Code:
declare -a testarry
testarry=("11"  "22"  "33" "44")
limit="`echo ${#testarry[@]}`" 
for ((i=0;i<=$limit;i++))
do 
echo ${testarry[$i]}
done

output:
Code:
11
22
33
44

OR as in your case simply :
Code:
declare -a testarry
testarry=("bin"  "barn"  "bin" "barn")
limit="`echo ${#testarry[@]}`"  
echo ${testarry[2]}

Keep in mind array count starts from 0.

hope it helps.
# 4  
Old 01-07-2011
Quote:
Originally Posted by Chubler_XL
[..]
Or change IFS (I like this solution because it looks a lot neater and avoids possible hyjacks):
Code:
string="bin|barn|bin, barn"
IFS="|" array=($string)

It is usually a good idea to save IFS before and reset it to its old value afterwards.
Code:
oldIFS=$IFS
IFS=... var=...... # some variable assignment with the other IFS
IFS=$oldIFS

Last edited by Scrutinizer; 01-07-2011 at 03:16 AM..
# 5  
Old 01-07-2011
Thanks, the IFS approach works perfectly.
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