Shell Script - List¶

For Loop:

#!/bin/bash

# construct a list this way:
text="a b c d e f g"
words=($text)

# or this:
#words=(a b c d e f g)

# or this:
#words=("a" "b" "c" "d" "e" "f" "g")

for i in "${words[@]}"
do
    echo $i
done

Slice:

#!/bin/bash

# the syntax ${var[@]: start_index:n_item}, from <start_index> index, select <n_item> items.
words=(0 1 2 3 4 5 6 7 8 9)

#---
echo ${words[@]: 0:1} # first item: 0
echo ${words[@]: 1:1} # second item: 1
echo ${words[@]: -1:1} # last: 9
echo ${words[@]: -2:1} # second last: 8

#---
echo ${words[@]: 3:5} # from index 3, select 5 items: 3 4 5 6 7
echo ${words[@]: -7:5} # from index -7, select 5 items: 3 4 5 6 7
start_index=3
n_item=5
echo ${words[@]: $start_index:$n_item} # from index 3, select 6 items: 3 4 5 6 7

#---
echo ${words[0]} # first item: 0
echo ${words[1]} # second item: 1
nth=2
echo ${words[$nth]} # third item: 2

#---
items=${words[@]: 3:5} # 3 4 5 6 7
items=($items) # construct a list
for i in "${items[@]}"
do
    echo $i
done