How to set array total elements in for loop

Question

I have the following code:

#!/bin/bash

SECTION[1]="900px"
PATH[1]="/path/to/folder"

SECTION[2]="1080px"
PATH[2]="/patj/to/folder2"

SECTION[3]="3000px"
PATH[3]="/patj/to/folder3"

for i in {1..3}
do
    echo "${SECTION[$i]}"
    echo "${PATH[$i]}"
done

How can I make the for loop iterate through the number of sections?

I tried:

for i in {1.."${#SECTION[@]}"}

But I get an operand expected error.

Works for me with bash 4.3.48 if I only use builtin commands.. This might help: linfo.org/path_env_var.html — Cyrus
– Cyrus, Commented Aug 15, 2019 at 10:36
I should have mentioned that I'm on macos, I think the bash default bash version is 3.2. — ThatDude
– ThatDude, Commented Aug 15, 2019 at 10:47

lw0v0wl · Accepted Answer · 2019-08-15 10:34:56Z

1

You can use the C like for loop syntax

for ((i=1;i <= ${#SECTION[@]};i++))
do 
    echo "${SECTION[$i]}"
    echo "${PATH[$i]}" 
done

Or with seq

for i in $(seq ${#SECTION[@]})
do 
    echo "${SECTION[$i]}"
    echo "${PATH[$i]}" 
done

answered Aug 15, 2019 at 10:34

lw0v0wl

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2 Comments

ThatDude Over a year ago

That seq example looks so much more elegant - thanks so much. Love this place :-)

lw0v0wl Over a year ago

seq one around ~20-30% faster based on my tests but it required the seq command to be available.

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