Shell script arrays

Question

I would like to set array elements with loop:

for i in 0 1 2 3 4 5 6 7 8 9
do
array[$i] = 'sg'
done

echo $array[0]
echo $array[1]

So it does not work. How to..?

Do you know the seq command? you could replace your numbers with $(seq 0 9) — Miquel
– Miquel, Commented Dec 17, 2011 at 16:06
You need to be careful, as some shells do not have arrays. If you want to writable portable sh, you cannot use arrays at all. — William Pursell
– William Pursell, Commented Dec 17, 2011 at 16:49

Oliver Charlesworth · Accepted Answer · 2011-12-17 16:04:21Z

7

Remove the spaces:

array[$i]='sg'

Also, you should access the elements as^*:

echo ${array[0]}

See e.g. http://tldp.org/LDP/abs/html/arrays.html.

_{* Thanks to @Mat for reminding me of this!}

answered Dec 17, 2011 at 16:04

Oliver Charlesworth

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Comments

Zsolt Botykai · Accepted Answer · 2011-12-17 16:09:39Z

2

It should work if you had declared your variable as array, and print it properly:

declare -a array
for i in 0 1 2 3 4 5 6 7 8 9 
do
    array[$i]="sg"
done
echo ${array[0]} 
echo ${array[1]}

See it in action here.

HTH

answered Dec 17, 2011 at 16:09

Zsolt Botykai

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Comments

glenn jackman · Accepted Answer · 2011-12-17 22:47:30Z

1

there is problem with your echo statement: give ${array[0]} and ${array[1]}

edited Dec 17, 2011 at 22:47

glenn jackman

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answered Dec 17, 2011 at 16:08

harish.venkat

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Praveen Kumar Verma · Accepted Answer · 2015-03-18 11:14:17Z

1

# Declare Array

NAMEOFSEARCHENGINE=( Google Yahoo Bing Blekko Rediff )

# get length of an array
arrayLength=${#NAMEOFSEARCHENGINE[@]}

# use for loop read all name of search engine
for (( i=0; i<${arrayLength}; i++ ));
do
  echo ${NAMEOFSEARCHENGINE[$i]}
done

Output:

Google
Yahoo
Bing
Blekko
Rediff

edited Mar 18, 2015 at 11:14

answered Mar 18, 2015 at 11:08

Praveen Kumar Verma

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Comments

sehe · Accepted Answer · 2011-12-18 19:52:17Z

0

My take on that loop:

array=( $(yes sg | head -n10) )

Or even simpler:

array=( sg sg sg sg sg sg sg sg sg sg )

See http://ideone.com/DsQOZ for some proof. Note also, bash 4+ readarray:

readarray array -t -n 10 < <(yes "whole lines in array" | head -n 10)

In fact, readarray is most versatile, e.g. get the top 10 PIDs of processes with bash in the name into array (which could return an array size<10 if there aren't 10 such processes):

readarray array -t -n 10 < <(pgrep -f bash)

edited Dec 18, 2011 at 19:52

answered Dec 18, 2011 at 19:42

sehe

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1 Comment

sehe Over a year ago

added readarray, which has it's place for allowing embedded whitespace easily

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