How to extract a value from a command output in a shell script?

Question

The Linux command is sudo parted /dev/sda unit s print free | tail -2. In my case it returns something like this:

        34605056s  67108830s  32503775s  Free Space

I need to capture the first number string and the second number string.

The goal is to create a new partition fitting the remaining free space perfectly.

I tried to use grep, but the best I could achieve was just getting colored matched numbers, but they can't be used in script as parameters:

sudo parted /dev/sda unit s print free | tail -2 | grep -oP '(\d+s\b)'

gives

34605056s
67108830s
32503775s

I need something that would return exactly '34605056s' and '67108830s' that I would be able to put into mkpart command.

tshiono · Accepted Answer · 2021-05-16 00:55:14Z

2

Would you please try:

read -r start end _ < <(sudo parted /dev/sda unit s print free | tail -2)

then you can pass the variables $start and $end to mkpart

answered May 16, 2021 at 0:55

tshiono

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Comments

iBug · Accepted Answer · 2021-05-16 00:35:09Z

2

AWK comes in handy:

echo "        34605056s  67108830s  32503775s  Free Space" |
  awk '{print $1, $2}'

Output:

34605056s 67108830s

answered May 16, 2021 at 0:35

iBug

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