LinuxQuestions.org - [SOLVED] Bash: back-referencing / shuffle string content using internals

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Bash: back-referencing / shuffle string content using internals

Code:

#!/bin/bash

# -------------------------------------------------------------------------- #

# Examples before and after:

#  01.foo.bar.ext      ->  foo.bar.01.ext

#  10.foo.txt          ->  foo.10.txt

#  9.foo.bar.fubar.cfg  ->  foo.bar.fubar.9.cfg

# -------------------------------------------------------------------------- #

tstStr01="01.foo.bar.ext"  

echo -e "\nOriginal string: $tstStr01"



echo -e "\n - Using Sed - - - - - - -\n"

echo $tstStr01 | sed -r 's/(01)\.(.*)\.(ext)/\2.\1.\3/'



echo -e "\n - Using Bash - - - - - - -\n"

strPrefix=${tstStr01%%.*}                # get prefix

strSuffix=${tstStr01##*.}                # get suffix

tmp1=${tstStr01%.*} ; strRest=${tmp1#*.}  # get "rest"

echo "$strRest.$strPrefix.$strSuffix"    # rebuild

As shown in the above code snippet using sed and back-referencing is a simple task but using bash internals it needs multiple steps to accomplish the same result.

Questions (about the bold part):
- Is it at all possible to use back-referencing when using parameter expansion? Haven't been able to find anything on-line about this.
- Is there a shorter, possibly more elegant way to do this?

Just to make sure: I'm looking for a bash internal solution and _not_ for an awk, perl, sed, etc solution.

How about:

Code:

#!/bin/bash



regex='([^.]+)\.(.*)\.(.{3})'



[[ "$1" =~ $regex ]] && echo "${BASH_REMATCH[2]}.${BASH_REMATCH[1]}.${BASH_REMATCH[3]}"

This gave me your required output for the 3 examples (Note: the sed will not :) )

Quote:

Originally Posted by grail (Post 5071500)

How about:

Code:

#!/bin/bash



regex='([^.]+)\.(.*)\.(.{3})'



[[ "$1" =~ $regex ]] && echo "${BASH_REMATCH[2]}.${BASH_REMATCH[1]}.${BASH_REMATCH[3]}"

This gave me your required output for the 3 examples

That's a really good alternative. Readable and compact.

Quote:

(Note: the sed will not :) )

Yeah..... Added the examples after I reread the finished post and forgot about the fixed ext part in the code.

Thanks!