I need to create a line in makefile which will extract the version from string, and will work cross-platform, ideally without dependencies.

This is what I had

echo "golangci-lint has version 1.42.0 built..." | grep -oP '\d \.\d \.\d'

retuslt: 1.42.0

But it doesn't work on mac.

Trying to do it with sed like this, but doesn't work

echo "golangci-lint has version 1.42.0 built ..." | sed -n  's/.*\(\d \.\d \.\d\).*/\1/p'

CodePudding user response：

grep -ow '[0-9][0-9.]\ [0-9]'

That uses only a basic regular expression, and options that BSD grep and GNU grep share.

CodePudding user response：

You can use

echo "golangci-lint has version 1.42.0 built ..." | sed -En  's/.*([0-9] \.[0-9] \.[0-9] ).*/\1/p'

Details:

• -E - enables the POSIX ERE syntax
• n - default line output is suppressed now
• .*([0-9] \.[0-9] \.[0-9] ).* - any text, then Group 1 capturing one or more digits, ., one or more digits, ., one or more digits and the rest of the line
• \1 - the replacement is just Group 1 value
• p - only the substitution result is printed.

CodePudding user response：

With your shown samples, you could try following awk program which will print only matched value of version out of whole line.

echo "golangci-lint has version 1.42.0 built ..." | 
awk '
{
  match($0,/[0-9] \.[0-9] \.[0-9] /)
  print substr($0,RSTART,RLENGTH)
}
'

Explanation: Simple explanation would be, printing line's value with echo command of shell here and sending its output as a standard input to awk code, where using match function to match mentioned regex in it. If there is a match then printing matched value.

Explanation of regex:

[0-9] \.[0-9] \.[0-9] : Matching 1 or more occurrences of digits followed by . followed by 1 or more occurrences of digits followed by another dot. followed by 1 or more digits.

CodePudding user response：

-P is an experimental feature in gnu-grep which is not available on Mac BSD. However default grep available in Mac can handle it easily with -E switch but you have to use [0-9] or [[:digit:]] in place of \d in your search pattern:

s="golangci-lint has version 1.42.0 built..."
grep -Eo '([0-9] \.) [0-9] ' <<< "$s"

# or else
grep -Eo '([[:digit:]] \.) [[:digit:]] ' <<< "$s"

1.42.0

As a side note I have gnu-grep installed on my Mac using home brew package.

CodePudding user response：

Suggesting the following:

echo "golangci-lint has version 1.42.0 built..." | grep -o '[0-9\.]\{4,\}'

Explanation

[0-9\.] --- match a single digit or dot(.)

\{4,\} --- the matched charterer 4 or more times.

CodePudding user response：

This awk is 100% POSIX:

awk 'match($0, /[0-9][0-9.] [0-9]/) {print substr($0, RSTART, RLENGTH)}'

It will always print the first match and only (up to) one match per line. There can be zero or more dots in the number, but leading/trailing dots won't get printed.

grep -o is quite portable, but not every platform supported by Go has it. Eg. IBM AIX. Also note that if a line has multiple matches, it will print each match on a new line.

CodePudding user response：

Using sed

$ echo "golangci-lint has version 1.42.0 built ..." | sed 's/[^0-9]*\([0-9.]*\) .*/\1/'
1.42.0