Bash：在数字之后提取字符串的一部分

Question

I have a few strings like this:

var1="string one=3423423 and something which i don't care"
var2="another bigger string=413145 and something which i don't care"
var3="the longest string ever=23442 and something which i don't care"

These strings are the output of a python script (which i am not allowed to touch), and I need a way to extract the 1st part of the string, right after the number. Basically, my outputs should be:

"string one=3423423"
"another bigger string=413145"
"the longest string ever=23442"

As you can see, i can't use positions, or stuff like that, because the number and the string length are not always the same. I assume i would need to use a regex or something, but i don't really understand regexes. Can you please help with a command or something which can do this?

Answer 1

grep -oP '^.*?=\d+' inputfile
string one=3423423
another bigger string=413145
the longest string ever=23442

Here -o flag will enable grep to print only matching part and -p will enable perl regex in grep . Here \\d+ means one or more digit. So, ^.*?=\\d+ means print from start of the line till you find last digit (first match).

Answer 2

You could use parameter expansion, for example:

var1="string one=3423423 and something which i don't care"
name=${var1%%=*}
value=${var1#*=}
value=${value%%[^0-9]*}
echo "$name=$value"
# prints: string one=3423423

Explanation of ${var1%%=*} :

• %% - remove the longest matching suffix
• = - match =
• * - match everything

Explanation of ${var1#*=} :

• # - remove the shortest matching prefix
• * - match everything
• = - match =

Explanation of ${value%%[^0-9]*} :

• %% - remove the longest matching suffix
• [^0-9] - match any non-digit
• * - match everything

To perform the same thing on more than one values easily, you could wrap this logic into a function:

extract_and_print() {
    local input=$1
    local name=${input%%=*}
    local value=${input#*=}
    value=${value%%[^0-9]*}
    echo "$name=$value"
}

extract_and_print "$var1"
extract_and_print "$var2"
extract_and_print "$var3"

Answer 3

$ shopt -s extglob

$ echo "${var1%%+([^0-9])}"
string one=3423423

$ echo "${var2%%+([^0-9])}"
another bigger string=413145

$ echo "${var3%%+([^0-9])}"
the longest string ever=23442

+([^0-9]) is an extended pattern that matches one or more non-digits.
${var%%+([^0-9])} with %%pattern will remove the longest match of that pattern from the end of the variable value.

Refs: patterns , parameter substitution