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List:       linux-newbie
Subject:    Re: leading spaces in a text file.
From:       Riley Williams <rhw () InfraDead ! Org>
Date:       2002-08-24 21:35:16
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Hi Matthew, Haines.

>> i have been formatting some texts for an online archive of e-texts.  
>> every once and a while i encounter a file that has leading spaces in
>> front of each sentence.  to remedy this problem i have used the 'tr'
>> utility to squeeze multiple occurrences of spaces.  this works very
>> nicely with the exception that the output file has a single leading
>> space at the beginning of each sentence. is there a better way of
>> doing this or of finishing this job?

> I don't know what you use as a text editor, but if it has a search
> and replace, you can readily remove multiple spaces. For example, I
> run emacs and use replace-string to replace a fixed number of
> multiple spaces at the beginning of each line with null.
> 
> This does not work with a single space at the start of each line,
> for replacing a single space with null removes the spaces between
> words. I don't know how to handle this situation.

There is an easy way to preprocess any text file such that all strings
of multiple tabs or spaces are replaced with a single space, and all
leading and trailing spaces are stripped. Use the following sequence...

    cat "$OLD" | tr -s '\t' ' ' | sed 's/^ //;s/ $//' > "$NEW"

...where "$OLD" is the file as it currently stands, and "$NEW" is the
file to create with the modified version in it. For reference...

 1. The command `tr -s '\t' ' '` says to replace all sequences of
    spaces and/or tabs with a single space.

 2. The command `sed 's/^ //;s/ $//'` says to remove a single
    leading and/or trailing space from each line.

...and the combination does exactly what you want.

Best wishes from Riley.

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