When gnu extensions are enabled, the only way to avoid newline as a
break character is to write all the break characters in the file with no
newline at all, not even at the end of the file. When gnu extensions
are disabled, spaces, tabs and newlines are always considered as break
characters even if not included in the Break file.
There is no default for the Only file. When both an Only file and an
Ignore file are specified, a word is considered a keyword only
if it is listed in the Only file and not in the Ignore file.
Using this option, the program does not try very hard to remove
references from contexts in output, but it succeeds in doing so
when the context ends exactly at the newline. If option
-r is used with -S default value, or when gnu extensions
are disabled, this condition is always met and references are completely
excluded from the output contexts.
[.?!][]\"')}]*\\($\\|\t\\| \\)[ \t\n]*
Whenever gnu extensions are disabled or if -r option is used, end of lines are used; in this case, the default regexp is just:
\n
Using an empty regexp is equivalent to completely disabling end of line or end of sentence recognition. In this case, the whole file is considered to be a single big line or sentence. The user might want to disallow all truncation flag generation as well, through option -F "". See Syntax of Regular Expressions.
When the keywords happen to be near the beginning of the input line or sentence, this often creates an unused area at the beginning of the output context line; when the keywords happen to be near the end of the input line or sentence, this often creates an unused area at the end of the output context line. The program tries to fill those unused areas by wrapping around context in them; the tail of the input line or sentence is used to fill the unused area on the left of the output line; the head of the input line or sentence is used to fill the unused area on the right of the output line.
As a matter of convenience to the user, many usual backslashed escape
sequences from the C language are recognized and converted to the
corresponding characters by ptx itself.
An empty regexp is equivalent to not using this option. See Syntax of Regular Expressions.
As a matter of convenience to the user, many usual backslashed escape sequences, as found in the C language, are recognized and converted to the corresponding characters by ptx itself.