Re: tr problem

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On Friday 13 June 2008, Les Mikesell wrote:
>Gene Heskett wrote:
>>>> I'm trying to convert a test file, src code for a legacy computer, whose
>>>> eol is a single cr into one with a newline subbed for each cr, and tr is
>>>> being a pita, it broken, or there is PEBKAC.
>>>> If I use this syntax:
>>>> tr -c \r \n <filename  >filename2
>>>> Then the whole file is converted to nnnnnnnnnn's, every byte.
>>>> The manpage (and pinfo tr too) is, shall we say, completely lacking in
>>>> how to handle the file I/O.
>>>> So how do you use tr?"
>>> Why option -c?
>>> tr '\r' '\n' <filename  >filename2
>>> would do it.
>> Cuz the manpage says that it triggers the character convert thing?
>No, tr actually takes 2 'sets' of characters even though in your use you
>only need one character in each set. For example
>tr '[A-Z]' '[a-z]'
>would lowercase a file (and the brackets and quotes aren't strictly
>necessary but would be on a sysV version).
>The -c option means to complement the first set (i.e. it becomes the
>characters not included).
>> It doesn't touch on its performance if the option isn't given.  And it
>> doesn't mention using the quotes either, but it worked just fine, thank
>> you very much.
>Man pages generally never mention the things the shell does to a command
>line before starting the program.  This will include expanding variables
>and wildcard filenames, redirecting I/O, and other things triggered by
>shell metacharacters.  In this case tr doesn't particularly need the
>quotes, but if you don't use them the shell will parse and remove the \
>characters (treating them as quotes for the following character in its
>own parsing).  These details are the same for every command you type (or
>script) and not repeated in every man page.
I got it working now, but once its done, I won't need it again till 3 years down 
the log, and will have forgotten it again.  Thanks Les.

Cheers, Gene
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