Looking for a somewhat clever way to do this.

I have an input file which consists of fixed length (10 characters) lines containing a-z.

For each line, I want to build and print a regexp string that I will use elsewhere.

The regexp string will begin (before processing each line):

'/bin/grep .......... /path/to/some/file'

For each 'x' character in the input file, I want to replace the corresponding dot in the regexp with say the corresponding digit of pi (1415926535).

For example, if a line in input file contains an 'x' in the third character (but not the first and second), the regexp string should become:

'/bin/grep ..1....... /path/to/some/file'

If the next 'x' occurs in the seventh character of the line, then the string should become:

'/bin/grep ..1...6... /path/to/some/file'

I feel like some simple way should exist to do this, but my attempts have just become a mess of code.

In reply to string substitution by Anonymous Monk

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