Bash Array Variable

Question

I am trying to write a script to execute a couple of different java/r programs but I am having an issue with using a value from an array in bash. Here is my example:

INPUTS[0]=$1 #file
INPUTS[1]=$2 #file
INPUTS[2]=$3 #file
INPUTS[3]=$4 #file
TARGET=$5 #file
OUTPUTS[0]=$6 #file
OUTPUTS[1]=$7 #file
OUTPUTS[2]=$8 #file
OUTPUTS[3]=$9 #file
TYPE=$10 #file
PANEL=$11 #String

for ((X=0;X<${#INPUTS[@]};X++));do #for every file in this array
   CURRENT="${INPUTS[X]}" #look at current in file
   CURRENTOUT="${OUTPUTS[X]}" #and current out file
   #this is working just fine. I put in a file myfile.txt and it makes a new file **results.txt**
   java -jar javathing.jar INPUT=$CURRENT TARG=$TARGET OUTPUT=$CURRENTOUT IS=True #run this
   #This is throwing an error because it can't find **results.txt0**
   java -jar morejava.jar -i $CURRENTOUT -o $TYPE #then this
done
Rscript rthing.R $TYPE $PANEL #finally

So my first java outputs the correct file with a correct file name- results.txt

But when my second java program goes to look for it, it looks for the incorrect name. It looks for results.txt0

I am using the same variable for each one, but it doesn't seem to have the same effect. Can anyone explain this behavior?

@CodeGnome I don't have those in my actual code. I was commenting just for the sake of this post. Does Stackoverflow have a comment character? As it seems there are at least 2 nitpickers I will change it. — user2076476
– user2076476, Commented Oct 11, 2013 at 17:17
Use the comment character of the language you're writing. # for bash — Barmar
– Barmar, Commented Oct 11, 2013 at 17:18
There's no way the variable CURRENTOUT can change between those two statements. — Barmar
– Barmar, Commented Oct 11, 2013 at 17:20
Not related to your problem, but you can set the arrays more concisely with INPUT=( "${@:1:4}" ) and OUTPUT=( "${@:6:4}" ). — chepner
– chepner, Commented Oct 11, 2013 at 17:25

Barmar · Accepted Answer · 2013-10-11 17:21:52Z

3

Fix these lines:

TYPE=$10 #file
PANEL=$11 #String

They should be:

TYPE=${10} #file
PANEL=${11} #String

From the bash man page:

When a positional parameter consisting of more than a single digit is expanded, it must be enclosed in braces (see EXPANSION below).

What you wrote was interpreted as:

TYPE=${1}0
PANEL=${1}1

answered Oct 11, 2013 at 17:21

Barmar

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3 Comments

user2076476 Over a year ago

Why would I do this for these two variables, but none of the others?

Barmar Over a year ago

Because the other positional parameters only have 1 digit.

Barmar Over a year ago

You can use the braces for the others if you like, you just don't need to.

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