BASH get major/minor version from string

Question

I am quite new BASH scripting and I am trying to create my own script to download/build from source a package. However I would like to add some interaction to my script to make it future ready for newer versions.

My script asks the user for the version they would like to install and generates the wget command and download link. See excerpt below:

# Ask user for required version
read packversion

# Download version from internet (depending on version provided above)
wget https://example.com/download/1.10/src/$packversion.tar.gz -O package.tar.gz

This works OK, however if you look at the url it contains 1.10, I would like to pull just the major/minor version from the provided string and pre-populate that also.

Is there a function I can use to achieve this?

Thanks in advance.

score 17 · Answer 1 · answered May 17 '18 at 21:37

17

In bash, I was able to do this:

» export packversion=1.10.2
» export shortversion=${packversion%.*}
» printenv shortversion
1.10

From Bash Pocket Reference by Arnold Robbins (O'Reilly, 2016, 2nd edition):

${var%pattern} Use value of var after removing text matching pattern from the left. Remove the shortest matching piece.

Here, {.*} is the pattern to be removed, which corresponds to the patch version number.

answered May 17 '18 at 21:37

spacewombat

171
1
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3

This is not ideal because if `packversion` is `1.10`, you end up with `shortversion` being `1`. OP probably wants to keep major and minor even if patch isn't specified. – Maros Apr 15 '20 at 08:13

score 12 · Accepted Answer · answered Mar 13 '18 at 10:43

12

I have managed to achieve what I was after by doing the following:

shortversion="$(cut -d '.' -f 1 <<< "$packversion")"."$(cut -d '.' -f 2 <<< "$packversion")"

This then creates a new variable which I can use to create the url.

wget https://example.com/download/$shortversion/src/package-$packversion.tar.gz

Though not sure if its the best way, works for me though.

answered Mar 13 '18 at 10:43

CrispyDuck

391
1
2
8

11

Shortcut: `cut -d '.' -f 1,2 <<< "$packversion"` – Pascal Polleunus Nov 19 '20 at 23:35

score 2 · Answer 3 · answered Nov 20 '22 at 12:37

2

since the right answer here is hidden in one of the comments, thanks to Pascal:

cut -d '.' -f 1,2 <<< "$packversion"

answered Nov 20 '22 at 12:37

bugkiller

124
3

Konstantin Vustin · Answer 4 · 2018-03-13T11:13:50.967

0

something like this?

$ cat script.sh 
#!/bin/bash
read packversion major minor
echo "https://example.com/download/${major}.${minor}/src/${packversion}.tar.gz -O package.tar.gz"

Result:

$ bash script.sh
foobar 2 25 # Input
https://example.com/download/2.25/src/foobar.tar.gz -O package.tar.gz

Edit: Use this:

#!/bin/bash
read packversion
if [[ $packversion =~ [0-9]+\.[0-9]+ ]]; then
  version=${BASH_REMATCH[0]}
else
  echo "Looks like \"$packversion\" doesn't contain proper version" && exit 1
fi
echo "https://example.com/download/${version}/src/${packversion}.tar.gz -O package.tar.gz"

Result:

$ bash 123.sh
something-1.2.3-else
https://example.com/download/1.2/src/something-1.2.3-else.tar.gz -O package.tar.gz

edited Mar 13 '18 at 11:13

answered Mar 13 '18 at 10:03

Konstantin Vustin

6,521
2
16
32

I don't really want to ask users for more input, they should just enter the one version and the script will do the rest. – CrispyDuck Mar 13 '18 at 10:06
Ok. Could you explain where does your script get major/minor version for URL? – Konstantin Vustin Mar 13 '18 at 10:14
When the script is run it asks the user to provide the full version (eg 1.2.3) I want to cut just 1.2 and put that in the url. I am just looking at the cut command now. – CrispyDuck Mar 13 '18 at 10:16
Can you provide a typical value of variable $packversion? – Konstantin Vustin Mar 13 '18 at 10:22
$packversion would contain 1.8.2 – CrispyDuck Mar 13 '18 at 10:23
I try to understand... it will be better to show full value, just to see what is the best way to split provided string, by delimiter or by regular expression, for example. – Konstantin Vustin Mar 13 '18 at 10:40

score 0 · Answer 5 · answered Jun 17 '23 at 22:15

If you want to extract all the version components individually (i.e., major, minor, and patch), you can do it like this:

#!/usr/bin/env bash

version=1.5.3

read major minor patch < <(echo $version | ( IFS=".$IFS" ; read a b c && echo $a $b $c ))

# Then you can use them like:
echo $major.$minor.$patch

BASH get major/minor version from string

5 Answers5