CODEWITHSUNDEEP
shellunixtcsh
user2741208
user2741208

Reputation: 13

can i iterate over the data in a variable in shell script?

So im learning shell script in school right now and i was working on this assignment and was stuck. Our prof/TA will be testing the answers to this questions by running simple commands like:

echo <random numbers>| sh question1

where random numbers can be anything. ie

echo 7 8| sh question1 So im not trying to get the answer to the assignment question but i have an idea of how to go about solving the question but, im hitting a bit of a snag out the gate.

I was trying something like this at the begining of my question1 file:

VAR1=tr -d [" "]

my thought process for this is that, i am trying to delete any spaces between the numbers it gives me and putting it in to a variable. but now im wondering how i can iterate over numbers in the variable

im probably 2-3 weeks into shell scripting and i learned python first so im not even sure if i can even iterate over it. But i thought there could be a way where i take the contents of a file, iterate over them and can access one char or integer at a time. is this even possible? i spent a lot of time trying to find a solution.

Any help would be great!

Upvotes: 0

Views: 820

Answers (2)

chepner
chepner

Reputation: 531878

An alternative approach to Vorsprung's answer would be to read a single line of input in your script, then use that to set that script's arguments. At the top of your script:

read line
set -- $line

Then you can use the same for loop:

for i in $*; do
    echo $i
done

This makes the same assumption as Vorsprung: the input will be a single line of space-separated values. If that assumption is false, I hope your instructors will be more specific about the type of input your script should be able to accept.

Upvotes: 0

Vorsprung
Vorsprung

Reputation: 34377

Does this example help?

for i in $* 
    do
    echo $i
done

$* is a list of the command line args, so running this as ./file.sh a b c will print a b c

Your input is apparently appearing on a pipe so next do this

echo 1 2 3 | xargs ./file.sh

xargs converts piped values into shell program parameter values

Upvotes: 3

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