Extracting specific string in a line with sed

Question

In a line of string like this:

"<testcase_name> +config=<main_cfg> +cfg1=<cfg1> +cfg2=<cfg2> +testlength=<string> +print_cfg=<string> +print_match=<string> +quit_count=<string>"

I would like to extract those strings that are after +cfg1= and +cfg2= only, and not including these specific configurations: +config= , +testlength= , +print_match= , +print_cfg= , and +quit_count= .

So I would like to store the result in a variable and be able to view it as:

echo "other_cfg = $other_cfg"
% other_cfg = cfg1.cfg2

Notice a . separates cfg1 and cfg2 strings. Is there a single line (if possible in sed) that can do this?

More conditions:

1. +cfg1 and +cfg2 could be any string AND there could be more of them. So the key here is to just not include these known configs: testlength , config , print_match , print_cfg , and quit_count .
2. The configs are not always in that order as the example above, except for +config= which is always the first one.
3. Any of the known configs mentioned in (1) may not be present in the line.

Examples:

Input 1:

testA +config=reg +input=walk1s +print_match=1 +testlength=short

Expected output 1:

% other_cfg = walk1s

Input 2:

testA +config=mem +quit_count=50 +order=reverse +input=rand +testlength=long

Expected output 2:

% other_cfg = reverse.rand

Answer 1

sed is for simple substitutions on individual lines, that is all. That's not what this problem is so it's not a job for sed, it's a job for awk.

$ cat file
"<testcase_name> +config=<main_cfg> +cfg1=<cfg1> +cfg2=<cfg2> +testlength=<string> +print_cfg=<string> +print_match=<string> +quit_count=<string>"
testA +config=reg +input=walk1s +print_match=1 +testlength=short
testA +config=mem +quit_count=50 +order=reverse +input=rand +testlength=long

$ cat tst.awk
BEGIN{
    FS="[ =]+"
    split("config testlength print_match print_cfg quit_count",tmp)
    for (i in tmp) {
        skip_cfgs["+"tmp[i]]
    }
}
{
    other_cfg = ""
    for (i=2;i<=NF;i+=2) {
        if ( !($i in skip_cfgs) ) {
            other_cfg = (other_cfg=="" ? "" : other_cfg ".") $(i+1)
        }
    }
    print "% other_cfg =", other_cfg
}

$ awk -f tst.awk file
% other_cfg = <cfg1>.<cfg2>
% other_cfg = walk1s
% other_cfg = reverse.rand

Answer 2

If +cfg1 and +cfg2 are guaranteed to always been in that order in the line, then yes; just subst out everything else:

sed 's/.*+cfg1=<//;s/>.*+cfg2=<//;s/>.*//'

Otherwise, you'll want at least awk .

Answer 3

This might work for you (GNU sed):

sed -r 's/^\S+\s+(.*)$/other_cfg = \1\n+config=+testlength=+print_match=+print_cfg=+quit_count=/;:a;s/ (\+\S+=)\S+(.*\n.*)\1/\2/;ta;s/ \+[^=]*=/./g;s/\./ /;P;d' file

This replaces the first string by the required one and adds a lookup table to the pattern space which includes all the config strings not needed. The unwanted config strings are then iteratively removed and remaining configs morphed into the required output.