@node Quoting
@section Quoting

@c Copyright (C) 2005, 2009--2021 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, no Front-Cover Texts, and no Back-Cover Texts.  A
@c copy of the license is at <https://www.gnu.org/licenses/fdl-1.3.en.html>.

@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}:

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

This differs from

@example
  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 @code{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.
