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(autocf21.info.gz) Printing Messages

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 6.4 Printing Messages
 =====================
 
 `configure' scripts need to give users running them several kinds of
 information.  The following macros print messages in ways appropriate
 for each kind.  The arguments to all of them get enclosed in shell
 double quotes, so the shell performs variable and backquote substitution
 on them.  You can print a message containing a comma by quoting the
 message with the `m4' quote characters:
 
      AC_MSG_RESULT([never mind, I found the BASIC compiler])
 
    These macros are all wrappers around the `echo' shell command.
 `configure' scripts should rarely need to run `echo' directly to print
 messages for the user.  Using these macros makes it easy to change how
 and when each kind of message is printed; such changes need only be
 made to the macro definitions, and all of the callers change
 automatically.
 
  -- Macro: AC_MSG_CHECKING (FEATURE-DESCRIPTION)
      Notify the user that `configure' is checking for a particular
      feature.  This macro prints a message that starts with `checking '
      and ends with `...' and no newline.  It must be followed by a call
      to `AC_MSG_RESULT' to print the result of the check and the
      newline.  The FEATURE-DESCRIPTION should be something like
      `whether the Fortran compiler accepts C++ comments' or `for c89'.
 
      This macro prints nothing if `configure' is run with the `--quiet'
      or `--silent' option.
 
  -- Macro: AC_MSG_RESULT (RESULT-DESCRIPTION)
      Notify the user of the results of a check.  RESULT-DESCRIPTION is
      almost always the value of the cache variable for the check,
      typically `yes', `no', or a file name.  This macro should follow a
      call to `AC_MSG_CHECKING', and the RESULT-DESCRIPTION should be
      the completion of the message printed by the call to
      `AC_MSG_CHECKING'.
 
      This macro prints nothing if `configure' is run with the `--quiet'
      or `--silent' option.
 
  -- Macro: AC_MSG_ERROR (ERROR-DESCRIPTION)
      Notify the user of an error that prevents `configure' from
      completing.  This macro prints an error message on the standard
      error output and exits `configure' with a nonzero status.
      ERROR-DESCRIPTION should be something like `invalid value $HOME
      for \$HOME'.
 
  -- Macro: AC_MSG_WARN (PROBLEM-DESCRIPTION)
      Notify the `configure' user of a possible problem.  This macro
      prints the message on the standard error output; `configure'
      continues running afterward, so macros that call `AC_MSG_WARN'
      should provide a default (back-up) behavior for the situations
      they warn about.  PROBLEM-DESCRIPTION should be something like `ln
      -s seems to make hard links'.
 
    The following two macros are an obsolete alternative to
 `AC_MSG_CHECKING' and `AC_MSG_RESULT'.
 
  -- Macro: AC_CHECKING (FEATURE-DESCRIPTION)
      This macro is similar to `AC_MSG_CHECKING', except that it prints a
      newline after the FEATURE-DESCRIPTION.  It is useful mainly to
      print a general description of the overall purpose of a group of
      feature checks, e.g.,
 
           AC_CHECKING(if stack overflow is detectable)
 
  -- Macro: AC_VERBOSE (RESULT-DESCRIPTION)
      This macro is similar to `AC_MSG_RESULT', except that it is meant
      to follow a call to `AC_CHECKING' instead of `AC_MSG_CHECKING'; it
      starts the message it prints with a tab.  It is considered
      obsolete.
 
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