using sed to replace two patterns within a larger pattern

Question

Using sed how could I replace two patterns within a larger pattern on a single line?

Given a single line of text I want to find a pattern (Let's call this the outer pattern) and then within that outer pattern replace two inner patterns.

Here's a one line example of the input text:

Z:\source\private\main\developer\foo\setenv.sh(25):     export 'FONTCONFIG_PATH'="$WINE_SHARED_SUPPORT/X11/etc/fonts"

In the example above the outer pattern is "/^.*([[:digit:]]+):/" which should equal "Z:\source\private\main\developer\foo\setenv.sh(25):" The two inner patterns are "/^[A-Za-z]:/" and "/\/".

Another way to phrase my question is: Using sed I know how to perform replacements of a pattern using the "s" command, but how do I limit the range of "s" command so it only works on the portion of the input string up to the "(25):"?

The ultimate result I am trying to get is the line of text is transformed into this:

/enlistments/source/private/main/developer/foo/setenv.sh(25):     export 'FONTCONFIG_PATH'="$WINE_SHARED_SUPPORT/X11/etc/fonts"

Answer 1

There are two facts that I think you'll find useful:

1. By default, sed will only replace the first occurrence of a string in a line. So given the following line:

   foo foo
   

   The command sed s/foo/bar/ will result in:

   bar foo
   

2. You can limit a sed command to lines matching a specific pattern. If you want to perform the above substitution only on lines containing the string "xyz", you would use a command like this:

   sed '/xyz/ s/foo/bar/'
   

I think this should help you do what you want.

Answer 2

This command converts your input example to your output example:

sed 's|\\|/|g;s|^[^/]*|/enlistments|'

If some of your input contains backslashes in the portion after the /^.*([[:digit:]]+):/ part, then you will have to divide and conquer to prevent those latter backslashes from being replaced.

sed 'h;s/^.*([[:digit:]]\+)://;x;s/^\(.*([[:digit:]]\+):\).*/\1/;s|\\|/|g;s|^[^/]*|/enlistments|;G;s/\n//'

Explanation (steps marked with an asterisk ([*]) apply to both commands):

• h - copy the line to hold space
• s/^.*([[:digit:]]\+):// - delete the first part of the line from the original in pattern space
• x - swap pattern space and hold space
• s/^\(.*([[:digit:]]\+):\).*/\1/ - keep the first part of the line from the copy (discard the last part)
• s|\\|/|g - [*] change all the backslashes to slashes (in the divide-and-conquer version, only the portion in pattern space - the first part of the line - is affected)
• s|^[^/]*|/enlistments| - [*] change whatever appears before the first slash into "/enlistments" - this could be made more selective if needed
• G - append a newline and the contents of hold space onto the end of pattern space
• s/\n// - remove the interior newline

Answer 3

You could try

sed -r 's/^[A-Z]:\\|\\/\//g' | sed 's/^/\/enlistments/'

Now, this of course requires that there's no backslashes in the part after (25): to work. But as I suspect this will never be the case due to unix path structure this will never be the case.