view doc/quote.texi @ 17321:896204e6fbfc

extensions: port better to MINUX 3, HP-UX, autoheader 2.62 Some of these changes are merged in from git Autoconf. * m4/extensions.m4 (AC_USE_SYSTEM_EXTENSIONS): When deciding whether to define _XOPEN_SOURCE, inspect the preprocessor macro __hpux instead of the more-heavyweight operation of requiring AC_CANONICAL_HOST. Define _NETBSD_HOST on MINUX, for MINUX 3. Use USE_SYSTEM_EXTENSIONS, not __EXTENSIONS__, as the key for __EXTENSIONS__.
author Paul Eggert <>
date Wed, 06 Feb 2013 22:41:08 -0800
parents e542fd46ad6f
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@node Quoting
@section Quoting

@c Copyright (C) 2005, 2009-2013 Free Software Foundation, Inc.

@c Permission is granted to copy, distribute and/or modify this document
@c under the terms of the GNU Free Documentation License, Version 1.3 or
@c any later version published by the Free Software Foundation; with no
@c Invariant Sections, with no Front-Cover Texts, and with no Back-Cover
@c Texts.  A copy of the license is included in the ``GNU Free
@c Documentation License'' file as part of this distribution.

@cindex Quoting
@findex quote
@findex quotearg

Gnulib provides @samp{quote} and @samp{quotearg} modules to help with
quoting text, such as file names, in messages to the user.  Here's an
example of using @samp{quote}:

#include <quote.h>
  error (0, errno, _("cannot change owner of %s"), quote (fname));
@end example

This differs from

  error (0, errno, _("cannot change owner of '%s'"), fname);
@end example

@noindent in that @code{quote} escapes unusual characters in
@code{fname}, e.g., @samp{'} and control characters like @samp{\n}.

@findex quote_n
However, a caveat: @code{quote} reuses the storage that it returns.
Hence if you need more than one thing quoted at the same time, you
need to use @code{quote_n}.

@findex quotearg_alloc
Also, the quote module is not suited for multithreaded applications.
In that case, you have to use @code{quotearg_alloc}, defined in the
@samp{quotearg} module, which is decidedly less convenient.