Bash capturing output of awk into array

Question

I am stuck on a little problem. I have a command which pipes output to awk but I want to capture the output of to an array one by one.

My example:

myarr=$(ps -u kdride | awk '{ print $1 }')

But that capture all my output into one giant string separated by commas:

output: PID 3856 5339 6483 10448 15313 15314 15315 15316 22348 29589 29593 32657 1

I also tried the following:

IFS=","
myarr=$(ps -u kdride | awk '{ print $1"," }')

But the output is: PID, 3856, 5339, 6483, 10448, 15293, 15294, 15295, 15296, 22348, 29589, 29593, 32657,
1

I want to be able to capture each individual pid into its own array element. Setting IFS = '\n' does not do anything and retains my original output. What change do I need to do to make this work?

You can skip the `awk` command altogether by using `myarr=( $(ps -u kdride -o pid) )`. (Note the extra parenthesis as pointed out in Paul's answer). — chepner, Feb 27 '13 at 13:56

score 106 · Accepted Answer · edited Feb 27 '13 at 06:11

106

Add additional parentheses, like this:

myarr=($(ps -u kdride | awk '{ print $1 }'))

# Now access elements of an array (change "1" to whatever you want)
echo ${myarr[1]}

# Or loop through every element in the array
for i in "${myarr[@]}"
do
   :
  echo $i
done

See also bash — Arrays.

edited Feb 27 '13 at 06:11

Jonathan Leffler

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answered Feb 27 '13 at 06:00

kamituel

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Ah much thanks. I skipped over that part entirely. Reference helps much thanks – Paul Feb 27 '13 at 06:20
7

What is the point of the : after the do? Why do we need a true here? I ran it without it and it still worked? – mmlac May 06 '16 at 20:24
1

I am also curious why there is a `:` – Azor Ahai -him- Jul 13 '16 at 17:52
1

I am also curious why there is a : please let us know – Millemila Jun 19 '17 at 13:16
1

Has anyone came to verdict on why there is a random colon? – DeadlyChambers Aug 03 '21 at 23:42
I have used this twice recently, works like a charm. But it looks like the mystery of the superfluous colon is still unsolved. – redlami May 25 '22 at 15:33

score 4 · Answer 2 · answered Aug 14 '19 at 17:55

4

Use Bash's builtin mapfile (or its synonym readarray)

mapfile -t -s 1 myarr < <(ps -u myusername | awk '{print $1}')

At least in GNU/Linux you can format output of ps, so no need for awk and -s 1

mapfile -t myarr < <(ps -u myusername -o pid=)

answered Aug 14 '19 at 17:55

jarno

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1

why do you need to use `<` twice? – baggiponte Jan 04 '22 at 16:37
2

@baggiponte It is because I am redirecting [process substitution](https://wiki.bash-hackers.org/syntax/expansion/proc_subst) – jarno Jan 05 '22 at 18:33

Bash capturing output of awk into array

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