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(standards.info)Errors

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Formatting Error Messages
=========================

   Error messages from compilers should look like this:

     SOURCE-FILE-NAME:LINENO: MESSAGE

If you want to mention the column number, use this format:

     SOURCE-FILE-NAME:LINENO:COLUMN: MESSAGE

Line numbers should start from 1 at the beginning of the file, and
column numbers should start from 1 at the beginning of the line.  (Both
of these conventions are chosen for compatibility.)  Calculate column
numbers assuming that space and all ASCII printing characters have
equal width, and assuming tab stops every 8 columns.

   Error messages from other noninteractive programs should look like
this:

     PROGRAM:SOURCE-FILE-NAME:LINENO: MESSAGE

when there is an appropriate source file, or like this:

     PROGRAM: MESSAGE

when there is no relevant source file.

   If you want to mention the column number, use this format:

     PROGRAM:SOURCE-FILE-NAME:LINENO:COLUMN: MESSAGE

   In an interactive program (one that is reading commands from a
terminal), it is better not to include the program name in an error
message.  The place to indicate which program is running is in the
prompt or with the screen layout.  (When the same program runs with
input from a source other than a terminal, it is not interactive and
would do best to print error messages using the noninteractive style.)

   The string MESSAGE should not begin with a capital letter when it
follows a program name and/or file name.  Also, it should not end with
a period.

   Error messages from interactive programs, and other messages such as
usage messages, should start with a capital letter.  But they should not
end with a period.