Bash looping through custom list of strings

Question

I'm trying to do a nested loop, one of which is indexing an array, but I also want to iterate through a custom list of strings, which happen to be only the letters C and I, nothing inbetween. My question is, what is the proper syntax for looping through this custom list of letters/strings? I saw some people use brackets{} to specify, what am I doing wrong?

abc=(thing1 thing2 thing3 thing4)

for j in C I; do
  for i in 0 1 2 3; do
    echo "grep 'ITEM_${abc[i]}' /folder1/folder2/THING_$jS_$i.sorted/585_10$jS_$i.sorted.gtf"
  done
done

And what exactly is the problem? I am guessing you don't want the echo there. — PesaThe
– PesaThe, Commented Aug 29, 2018 at 20:12
Problem is I want to iterate through two folder types and end with two output types, one with iterated C and separately, I (for each j) of the array — Sam Grow
– Sam Grow, Commented Aug 29, 2018 at 20:15
Showing your desired output would be a good place to start towards making this answerable. BTW, are you writing $jS_ when you want ${j}S_? — Charles Duffy
– Charles Duffy, Commented Aug 29, 2018 at 20:23

glenn jackman · Accepted Answer · 2018-08-29 22:16:29Z

1

your quotes are wrong : Don't use single quotes around variables
separate variables from the surrounding text with ${var}, ex : /THING_${j}S_${i}.sorted

Learn how to quote properly in shell, it's very important :

"Double quote" every literal that contains spaces/metacharacters and every expansion: "$var", "$(command "$var")", "${array[@]}", "a & b". Use 'single quotes' for code or literal $'s: 'Costs $5 US', ssh host 'echo "$HOSTNAME"'. See http://mywiki.wooledge.org/Quotes
http://mywiki.wooledge.org/Arguments
http://wiki.bash-hackers.org/syntax/words

edited Aug 29, 2018 at 22:16

glenn jackman

249k42 gold badges233 silver badges362 bronze badges

answered Aug 29, 2018 at 20:23

Mévatlavé Kraspek

7314 silver badges25 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Charles Duffy Over a year ago

We already have duplicate Q&A entries for both of the problems identified in this answer. If a question doesn't raise any new issues, it's typically appropriate to vote to close as duplicate (it's possible to have more than one duplicate linked to a single question, though it might need someone with enough rep to edit the dup list directly to enact that).

Sam Grow Over a year ago

Thank you, however this is addressing the format of my code in terms of some sort of hierarchical guideline for readability, but doesn't actually address the core of my question.

Sam Grow Over a year ago

Your code "fix" still doesn't answer the core of my question. It is iterating through a set of arbitrary letters that I don't want it to, but I'm going to fix it on my own with another array I guess. Could have used a simple reply like, no, you can't iterate through a custom set of loop arguments. Instead, "you're wrong learn how to do this properly". Thanks for your patronizing comment.

Sam Grow · Accepted Answer · 2018-08-30 15:30:49Z

0

Since other users won't answer the question and instead want to brigade over proper quoting, which doesn't actually address what the original question is about, the answer is simply, you need to create a custom array that is composed of just C and I which you can call for each instance of said file you are trying to edit the name of.

answered Aug 30, 2018 at 15:30

Sam Grow

113 bronze badges

Collectives™ on Stack Overflow

Bash looping through custom list of strings

2 Answers 2

3 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related