gen/FreeBSD/wordexp.3

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  26 .\" $FreeBSD$
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  28 .Dd July 29, 2004
  29 .Dt WORDEXP 3
  30 .Os
  31 .Sh NAME
  32 .Nm wordexp
  33 .Nd "perform shell-style word expansions"
  34 .\" .Sh LIBRARY
  35 .\" .Lb libc
  36 .Sh SYNOPSIS
  37 .In wordexp.h
  38 .Ft int
  39 .Fn wordexp "const char * restrict words" "wordexp_t * restrict we" "int flags"
  40 .Ft void
  41 .Fn wordfree "wordexp_t *we"
  42 .Sh DESCRIPTION
  43 The
  44 .Fn wordexp
  45 function performs shell-style word expansion on
  46 .Fa words
  47 and places the list of words into the
  48 .Va we_wordv
  49 member of
  50 .Fa we ,
  51 and the number of words into
  52 .Va we_wordc .
  53 .Pp
  54 The
  55 .Fa flags
  56 argument is the bitwise inclusive OR of any of the following constants:
  57 .Bl -tag -width ".Dv WRDE_SHOWERR"
  58 .It Dv WRDE_APPEND
  59 Append the words to those generated by a previous call to
  60 .Fn wordexp .
  61 .It Dv WRDE_DOOFFS
  62 As many
  63 .Dv NULL
  64 pointers as are specified by the
  65 .Va we_offs
  66 member of
  67 .Fa we
  68 are added to the front of
  69 .Va we_wordv .
  70 .It Dv WRDE_NOCMD
  71 Disallow command substitution in
  72 .Fa words .
  73 See the note in
  74 .Sx BUGS
  75 before using this.
  76 .It Dv WRDE_REUSE
  77 The
  78 .Fa we
  79 argument was passed to a previous successful call to
  80 .Fn wordexp
  81 but has not been passed to
  82 .Fn wordfree .
  83 The implementation may reuse the space allocated to it.
  84 .It Dv WRDE_SHOWERR
  85 Do not redirect shell error messages to
  86 .Pa /dev/null .
  87 .It Dv WRDE_UNDEF
  88 Report error on an attempt to expand an undefined shell variable.
  89 .El
  90 .Pp
  91 The
  92 .Vt wordexp_t
  93 structure is defined in
  94 .In wordexp.h
  95 as:
  96 .Bd -literal -offset indent
  97 typedef struct {
  98         size_t  we_wordc;       /* count of words matched */
  99         char    **we_wordv;     /* pointer to list of words */
 100         size_t  we_offs;        /* slots to reserve in we_wordv */
 101 } wordexp_t;
 102 .Ed
 103 .Pp
 104 The
 105 .Fn wordfree
 106 function frees the memory allocated by
 107 .Fn wordexp .
 108 .Sh IMPLEMENTATION NOTES
 109 The
 110 .Fn wordexp
 111 function is implemented as a wrapper around the undocumented
 112 .Ic wordexp
 113 shell built-in command.
 114 .Sh RETURN VALUES
 115 The
 116 .Fn wordexp
 117 function returns zero if successful, otherwise it returns one of the following
 118 error codes:
 119 .Bl -tag -width ".Dv WRDE_NOSPACE"
 120 .It Dv WRDE_BADCHAR
 121 The
 122 .Fa words
 123 argument contains one of the following unquoted characters:
 124 .Aq newline ,
 125 .Ql | ,
 126 .Ql & ,
 127 .Ql \&; ,
 128 .Ql < ,
 129 .Ql > ,
 130 .Ql \&( ,
 131 .Ql \&) ,
 132 .Ql { ,
 133 .Ql } .
 134 .It Dv WRDE_BADVAL
 135 An attempt was made to expand an undefined shell variable and
 136 .Dv WRDE_UNDEF
 137 is set in
 138 .Fa flags .
 139 .It Dv WRDE_CMDSUB
 140 An attempt was made to use command substitution and
 141 .Dv WRDE_NOCMD
 142 is set in
 143 .Fa flags .
 144 .It Dv WRDE_NOSPACE
 145 Not enough memory to store the result.
 146 .It Dv WRDE_SYNTAX
 147 Shell syntax error in
 148 .Fa words .
 149 .El
 150 .Pp
 151 The
 152 .Fn wordfree
 153 function returns no value.
 154 .Sh ENVIRONMENT
 155 .Bl -tag -width ".Ev IFS"
 156 .It Ev IFS
 157 Field separator.
 158 .El
 159 .Sh EXAMPLES
 160 Invoke the editor on all
 161 .Pa .c
 162 files in the current directory
 163 and
 164 .Pa /etc/motd
 165 (error checking omitted):
 166 .Bd -literal -offset indent
 167 wordexp_t we;
 168
 169 wordexp("${EDITOR:-vi} *.c /etc/motd", &we, 0);
 170 execvp(we.we_wordv[0], we.we_wordv);
 171 .Ed
 172 .Sh DIAGNOSTICS
 173 Diagnostic messages from the shell are written to the standard error output
 174 if
 175 .Dv WRDE_SHOWERR
 176 is set in
 177 .Fa flags .
 178 .Sh SEE ALSO
 179 .Xr sh 1 ,
 180 .Xr fnmatch 3 ,
 181 .Xr glob 3 ,
 182 .Xr popen 3 ,
 183 .Xr system 3
 184 .Sh STANDARDS
 185 The
 186 .Fn wordexp
 187 and
 188 .Fn wordfree
 189 functions conform to
 190 .St -p1003.1-2001 .
 191 .Sh BUGS
 192 Do not pass untrusted user data to
 193 .Fn wordexp ,
 194 regardless of whether the
 195 .Dv WRDE_NOCMD
 196 flag is set.
 197 The
 198 .Fn wordexp
 199 function attempts to detect input that would cause commands to be
 200 executed before passing it to the shell
 201 but it does not use the same parser so it may be fooled.
 202 .Pp
 203 The current
 204 .Fn wordexp
 205 implementation does not recognize multibyte characters, since the
 206 shell (which it invokes to perform expansions) does not.