Increment Letter on a Command Line

rashley has asked for the wisdom of the Perl Monks concerning the following question:

I have a shell script that calls a Perl one-liner to increment a letter.

NEXTBUILDLETTER=$(perl -e "\$x=ord($BUILDLETTER); \$x++; printf(\"%c\n
+\", \$x);")
[download]

The problem is... you guessed it... it chokes when it gets to N because the \n gets interpreted as a newline.

I've played with it forever now, and I can't seem to find a way around this. Thoughts?

Comment on Increment Letter on a Command Line Download Code

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Re: Increment Letter on a Command Line by Fletch (Bishop) on Feb 06, 2008 at 21:09 UTC
No need to convert to an integer and what not; `++` does the right thing. You also can cure some of your backwhackitis by just passing the current letter as an argument rather than trying to get it to interpolate. `NEXTBUILDLETTER=$( perl -le '$l=shift;print++$l' $BUILDLETTER )` [download] Update: Also keep in mind that that's going to behave slightly saner than using ord, for some value of sane where "AA" follows "Z" rather than "[". The cake is a lie. The cake is a lie. The cake is a lie.	[reply] [d/l] [select]
Re^2: Increment Letter on a Command Line by rashley (Scribe) on Feb 07, 2008 at 14:55 UTC
This was exactly what I was looking for. Thanks!	[reply]
Re: Increment Letter on a Command Line by moritz (Cardinal) on Feb 06, 2008 at 21:10 UTC
You can avoid the many escapes by using single quotes and reading the letter from STDIN: `$ echo 'a' \| perl -pe 'chomp; $_++; $_.=$/' b` [download] This uses the magic increment, not by ascii values - but you get the picture.	[reply] [d/l]
Re^2: Increment Letter on a Command Line by graff (Chancellor) on Feb 07, 2008 at 04:49 UTC
Don't forget "-l" (for chomping on input and adding $/ on output). It really helps keep your one-liners slim and trim: `$ echo 'a' \| perl -lpe '$_++;' b` [download]	[reply] [d/l]