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209 lines
5 KiB
Groff
209 lines
5 KiB
Groff
.\"
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.\" Copyright (c) 2002 Tim J. Robbins
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.Dd September 30, 2015
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.Dt WORDEXP 3
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.Os
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.Sh NAME
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.Nm wordexp
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.Nd "perform shell-style word expansions"
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In wordexp.h
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.Ft int
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.Fn wordexp "const char * restrict words" "wordexp_t * restrict we" "int flags"
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.Ft void
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.Fn wordfree "wordexp_t *we"
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.Sh DESCRIPTION
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The
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.Fn wordexp
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function performs shell-style word expansion on
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.Fa words
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and places the list of words into the
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.Va we_wordv
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member of
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.Fa we ,
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and the number of words into
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.Va we_wordc .
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.Pp
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The
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.Fa flags
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argument is the bitwise inclusive OR of any of the following constants:
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.Bl -tag -width ".Dv WRDE_SHOWERR"
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.It Dv WRDE_APPEND
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Append the words to those generated by a previous call to
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.Fn wordexp .
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.It Dv WRDE_DOOFFS
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As many
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.Dv NULL
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pointers as are specified by the
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.Va we_offs
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member of
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.Fa we
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are added to the front of
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.Va we_wordv .
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.It Dv WRDE_NOCMD
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Disallow command substitution in
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.Fa words .
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See the note in
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.Sx BUGS
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before using this.
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.It Dv WRDE_REUSE
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The
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.Fa we
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argument was passed to a previous successful call to
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.Fn wordexp
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but has not been passed to
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.Fn wordfree .
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The implementation may reuse the space allocated to it.
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.It Dv WRDE_SHOWERR
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Do not redirect shell error messages to
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.Pa /dev/null .
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.It Dv WRDE_UNDEF
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Report error on an attempt to expand an undefined shell variable.
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.El
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.Pp
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The
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.Vt wordexp_t
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structure is defined in
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.In wordexp.h
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as:
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.Bd -literal -offset indent
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typedef struct {
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size_t we_wordc; /* count of words matched */
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char **we_wordv; /* pointer to list of words */
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size_t we_offs; /* slots to reserve in we_wordv */
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} wordexp_t;
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.Ed
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.Pp
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The
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.Fn wordfree
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function frees the memory allocated by
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.Fn wordexp .
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.Sh IMPLEMENTATION NOTES
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The
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.Fn wordexp
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function is implemented using the undocumented
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.Ic freebsd_wordexp
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shell built-in command.
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.Sh RETURN VALUES
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The
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.Fn wordexp
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function returns zero if successful, otherwise it returns one of the following
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error codes:
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.Bl -tag -width ".Dv WRDE_NOSPACE"
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.It Dv WRDE_BADCHAR
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The
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.Fa words
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argument contains one of the following unquoted characters:
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.Aq newline ,
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.Ql | ,
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.Ql & ,
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.Ql \&; ,
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.Ql < ,
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.Ql > ,
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.Ql \&( ,
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.Ql \&) ,
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.Ql { ,
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.Ql } .
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.It Dv WRDE_BADVAL
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An error after successful parsing,
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such as an attempt to expand an undefined shell variable with
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.Dv WRDE_UNDEF
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set in
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.Fa flags .
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.It Dv WRDE_CMDSUB
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An attempt was made to use command substitution and
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.Dv WRDE_NOCMD
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is set in
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.Fa flags .
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.It Dv WRDE_NOSPACE
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Not enough memory to store the result or
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an error during
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.Xr fork 2 .
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.It Dv WRDE_SYNTAX
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Shell syntax error in
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.Fa words .
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.El
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.Pp
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The
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.Fn wordfree
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function returns no value.
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.Sh ENVIRONMENT
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.Bl -tag -width ".Ev IFS"
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.It Ev IFS
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Field separator.
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.El
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.Sh EXAMPLES
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Invoke the editor on all
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.Pa .c
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files in the current directory
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and
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.Pa /etc/motd
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(error checking omitted):
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.Bd -literal -offset indent
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wordexp_t we;
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wordexp("${EDITOR:-vi} *.c /etc/motd", &we, 0);
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execvp(we.we_wordv[0], we.we_wordv);
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.Ed
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.Sh DIAGNOSTICS
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Diagnostic messages from the shell are written to the standard error output
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if
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.Dv WRDE_SHOWERR
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is set in
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.Fa flags .
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.Sh SEE ALSO
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.Xr sh 1 ,
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.Xr fnmatch 3 ,
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.Xr glob 3 ,
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.Xr popen 3 ,
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.Xr system 3
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.Sh STANDARDS
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The
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.Fn wordexp
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and
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.Fn wordfree
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functions conform to
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.St -p1003.1-2001 .
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.Sh BUGS
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The current
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.Fn wordexp
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implementation does not recognize multibyte characters other than UTF-8, since
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the shell (which it invokes to perform expansions) does not.
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.Sh SECURITY CONSIDERATIONS
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Pathname generation may create output that is exponentially larger than the
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input size.
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.Pp
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Although this implementation detects command substitution reliably for
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.Dv WRDE_NOCMD ,
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the attack surface remains fairly large.
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Also, some other implementations
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(such as older versions of this one)
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may execute command substitutions even if
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.Dv WRDE_NOCMD
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is set.
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