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Infinite Recursion · Aug 16th, 2006, 8:43 PM

I'd like to see more entries in this section also... maybe a weekly script challenge or something.

#!/usr/bin/sed -f

# reverse all chars of each line, keep line ordering

# ignore empty lines, i.e. nothing to reverse
/./!b

# escape ! by doubling it, place markers at beginning and end of line
# the markers are -!- which can never happen after the escaping of !
s/!/!!/g
s/^/-!-/
s/$/-!-/

# swaps first char after first maker, with first char before last marker
# and then advance the markers through the swapped chars
ta
:a
s/-!-\([^!]\|!!\)\(.*\)\([^!]\|!!\)-!-/\3-!-\2-!-\1/
ta

# delete markers, and then unescape the !s
s/-!-//g
s/!!/!/g

ir@grendel [~/code/sed]# echo "hi there" | ./s.sh
ereht ih

Aug 16th, 2006, 8:43 PM	#2
Infinite Recursion Programming Guru Join Date: Jul 2004 Location: United States Posts: 3,466 Rep Power: 8	I'd like to see more entries in this section also... maybe a weekly script challenge or something. (Toggle Plain Text) #!/usr/bin/sed -f # reverse all chars of each line, keep line ordering # ignore empty lines, i.e. nothing to reverse /./!b # escape ! by doubling it, place markers at beginning and end of line # the markers are -!- which can never happen after the escaping of ! s/!/!!/g s/^/-!-/ s/$/-!-/ # swaps first char after first maker, with first char before last marker # and then advance the markers through the swapped chars ta :a s/-!-\([^!]\\|!!\)\(.\)\([^!]\\|!!\)-!-/\3-!-\2-!-\1/ ta # delete markers, and then unescape the !s s/-!-//g s/!!/!/g #!/usr/bin/sed -f # reverse all chars of each line, keep line ordering # ignore empty lines, i.e. nothing to reverse /./!b # escape ! by doubling it, place markers at beginning and end of line # the markers are -!- which can never happen after the escaping of ! s/!/!!/g s/^/-!-/ s/$/-!-/ # swaps first char after first maker, with first char before last marker # and then advance the markers through the swapped chars ta :a s/-!-\([^!]\\|!!\)\(.\)\([^!]\\|!!\)-!-/\3-!-\2-!-\1/ ta # delete markers, and then unescape the !s s/-!-//g s/!!/!/g ir@grendel [~/code/sed]# echo "hi there" \| ./s.sh ereht ih __________________ http://jasonpowers.net "There are a thousand hacking at the branches of evil to one who is striking at the root."