code / bp

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   2 .\"
   3 .TH "BP" "1" "May 17 2021" "" ""
   4 .SH NAME
   5 bp - Bruce\[aq]s Parsing Expression Grammar tool
   6 .SH SYNOPSIS
   7 \f[B]bp\f[R] [\f[I]options\&...\f[R]] \f[I]pattern\f[R] [[\f[B]--\f[R]]
   8 \f[I]files\&...\f[R]]
   9 .SH DESCRIPTION
  10 \f[B]bp\f[R] is a tool that matches parsing expression grammars using a
  11 custom syntax.
  12 .SH OPTIONS
  13 .TP
  14 \f[I]pattern\f[R]
  15 The text to search for.
  16 The main argument for \f[B]bp\f[R] is a string literals which may
  17 contain BP syntax patterns.
  18 See the \f[B]STRING PATTERNS\f[R] section below.
  19 .TP
  20 \f[B]-w\f[R], \f[B]--word\f[R] \f[I]word\f[R]
  21 Surround a string pattern with word boundaries (equivalent to \f[B]bp
  22 \[aq]{|}word{|}\[aq]\f[R])
  23 .TP
  24 \f[B]-e\f[R], \f[B]--explain\f[R]
  25 Print a visual explanation of the matches.
  26 .TP
  27 \f[B]-l\f[R], \f[B]--list-files\f[R]
  28 Print only the names of files containing matches instead of the matches
  29 themselves.
  30 .TP
  31 \f[B]-c\f[R], \f[B]--case\f[R]
  32 Perform pattern matching with case-sensitivity (the default is smart
  33 casing, i.e.\ case-insensitive, unless there are any uppercase letters
  34 present).
  35 .TP
  36 \f[B]-i\f[R], \f[B]--ignore-case\f[R]
  37 Perform pattern matching case-insensitively.
  38 .TP
  39 \f[B]-I\f[R], \f[B]--inplace\f[R]
  40 Perform filtering or replacement in-place (i.e.\ overwrite files with
  41 new content).
  42 .TP
  43 \f[B]-r\f[R], \f[B]--replace\f[R] \f[I]replacement\f[R]
  44 Replace all occurrences of the main pattern with the given string.
  45 .TP
  46 \f[B]-s\f[R], \f[B]--skip\f[R] \f[I]pattern\f[R]
  47 While looking for matches, skip over \f[I]pattern\f[R] occurrences.
  48 This can be useful for behavior like \f[B]bp -s string\f[R] (avoiding
  49 matches inside string literals).
  50 .TP
  51 \f[B]-g\f[R], \f[B]--grammar\f[R] \f[I]grammar-file\f[R]
  52 Load the grammar from the given file.
  53 See the \f[B]GRAMMAR FILES\f[R] section for more info.
  54 .TP
  55 \f[B]-G\f[R], \f[B]--git\f[R]
  56 Use \f[B]git\f[R] to get a list of files.
  57 Remaining file arguments (if any) are passed to \f[B]git --ls-files\f[R]
  58 instead of treated as literal files.
  59 .TP
  60 \f[B]-B\f[R], \f[B]--context-before\f[R] \f[I]N\f[R]
  61 The number of lines of context to print before each match (default: 0).
  62 See \f[B]--context\f[R] below for details on \f[B]none\f[R] or
  63 \f[B]all\f[R].
  64 .TP
  65 \f[B]-A\f[R], \f[B]--context-after\f[R] \f[I]N\f[R]
  66 The number of lines of context to print after each match (default: 0).
  67 See \f[B]--context\f[R] below for details on \f[B]none\f[R] or
  68 \f[B]all\f[R].
  69 .TP
  70 \f[B]-C\f[R], \f[B]--context\f[R] \f[I]N\f[R]
  71 The number of lines to print before and after each match (default: 0).
  72 If \f[I]N\f[R] is \f[B]none\f[R], print only the exact text of the
  73 matches.
  74 If \f[I]N\f[R] is \f[B]\[lq]all\[rq]\f[R], print all text before and
  75 after each match.
  76 .TP
  77 \f[B]-f\f[R], \f[B]--format\f[R] \f[I]fancy\f[R]|\f[I]plain\f[R]|\f[I]bare\f[R]|\f[I]file:line\f[R]|\f[I]auto\f[R]
  78 Set the output format.
  79 \f[I]fancy\f[R] includes colors and line numbers, \f[I]plain\f[R] prints
  80 line numbers with no coloring, \f[I]bare\f[R] prints only the match
  81 text, \f[I]file:line\f[R] prints the filename and line number for each
  82 match (grep-style), and \f[I]auto\f[R] (the default) uses
  83 \f[I]fancy\f[R] formatting when the output is a TTY and \f[I]bare\f[R]
  84 formatting otherwise.
  85 .TP
  86 \f[B]-h\f[R], \f[B]--help\f[R]
  87 Print the usage and exit.
  88 .TP
  89 \f[I]files\&...\f[R]
  90 The input files to search.
  91 If no input files are provided and data was piped in, that data will be
  92 used instead.
  93 If neither are provided, \f[B]bp\f[R] will search through all files in
  94 the current directory and its subdirectories (recursively).
  95 .SH STRING PATTERNS
  96 One of the most common use cases for pattern matching tools is matching
  97 plain, literal strings, or strings that are primarily plain strings,
  98 with one or two patterns.
  99 \f[B]bp\f[R] is designed around this fact.
 100 The default mode for bp patterns is \[lq]string pattern mode\[rq].
 101 In string pattern mode, all characters are interpreted literally except
 102 for curly braces \f[B]{}\f[R], which mark a region of BP syntax patterns
 103 (see the \f[B]PATTERNS\f[R] section below).
 104 In other words, when passing a search query to \f[B]bp\f[R], you do not
 105 need to escape periods, quotation marks, backslashes, or any other
 106 character, as long as it fits inside a shell string literal.
 107 In order to match a literal \f[B]{\f[R], you can either search for the
 108 character literal: \f[B]{\[ga]{}\f[R], the string literal:
 109 \f[B]{\[dq]{\[dq]}\f[R], or a pair of matching curly braces using the
 110 \f[B]braces\f[R] rule: \f[B]{braces}\f[R].
 111 .SH PATTERNS
 112 \f[B]bp\f[R] patterns are based off of a combination of Parsing
 113 Expression Grammars and regular expression syntax.
 114 The syntax is designed to map closely to verbal descriptions of the
 115 patterns, and prefix operators are preferred over suffix operators (as
 116 is common in regex syntax).
 117 Patterns are whitespace-agnostic, so they work the same regardless of
 118 whether whitespace is present or not, except for string literals
 119 (\f[B]\[aq]...\[aq]\f[R] and \f[B]\[dq]...\[dq]\f[R]), character
 120 literals (\f[B]\[ga]\f[R]), and escape sequences (\f[B]\[rs]\f[R]).
 121 Whitespace between patterns or parts of a pattern should be used for
 122 clarity, but it will not affect the meaning of the pattern.
 123 .TP
 124 \f[I]pat1 pat2\f[R]
 125 A sequence: \f[I]pat1\f[R] followed by \f[I]pat2\f[R]
 126 .TP
 127 \f[I]pat1\f[R] \f[B]/\f[R] \f[I]pat2\f[R]
 128 A choice: \f[I]pat1\f[R], or if it doesn\[aq]t match, then
 129 \f[I]pat2\f[R]
 130 .TP
 131 \f[B].\f[R]
 132 The period pattern matches single character (excluding newline)
 133 .TP
 134 \f[B]\[ha]\f[R]
 135 Start of a line
 136 .TP
 137 \f[B]\[ha]\[ha]\f[R]
 138 Start of the text
 139 .TP
 140 \f[B]$\f[R]
 141 End of a line (does not include newline character)
 142 .TP
 143 \f[B]$$\f[R]
 144 End of the text
 145 .TP
 146 \f[B]_\f[R]
 147 Zero or more whitespace characters, including spaces and tabs, but not
 148 newlines.
 149 .TP
 150 \f[B]__\f[R]
 151 Zero or more whitespace characters, including spaces, tabs, newlines,
 152 and comments.
 153 Comments are undefined by default, but may be defined by a separate
 154 grammar file.
 155 See the \f[B]GRAMMAR FILES\f[R] section for more info.
 156 .TP
 157 \f[B]\[dq]foo\[dq]\f[R], \f[B]\[aq]foo\[aq]\f[R]
 158 The literal string \f[B]\[lq]foo\[rq]\f[R].
 159 Single and double quotes are treated the same.
 160 Escape sequences are not allowed.
 161 .TP
 162 \f[B]\[ga]\f[R]\f[I]c\f[R]
 163 The literal character \f[I]c\f[R] (e.g.\ \f[B]\[ga]\[at]\f[R] matches
 164 the \[lq]\[at]\[rq] character)
 165 .TP
 166 \f[B]\[ga]\f[R]\f[I]c1\f[R]\f[B]-\f[R]\f[I]c2\f[R]
 167 The character range \f[I]c1\f[R] to \f[I]c2\f[R]
 168 (e.g.\ \f[B]\[ga]a-z\f[R]).
 169 Multiple ranges can be combined with a comma
 170 (e.g.\ \f[B]\[ga]a-z,A-Z\f[R]).
 171 .TP
 172 \f[B]\[ga]\f[R]\f[I]c1\f[R]\f[B],\f[R]\f[I]c2\f[R]
 173 Any one of the given character or character ranges \f[I]c1\f[R] or
 174 \f[I]c2\f[R] (e.g.\ \f[B]\[ga]a,e,i,o,u,0-9\f[R])
 175 .TP
 176 \f[B]\[rs]\f[R]\f[I]esc\f[R]
 177 An escape sequence (e.g.\ \f[B]\[rs]n\f[R], \f[B]\[rs]x1F\f[R],
 178 \f[B]\[rs]033\f[R], etc.)
 179 .TP
 180 \f[B]\[rs]\f[R]\f[I]esc1\f[R]\f[B]-\f[R]\f[I]esc2\f[R]
 181 An escape sequence range from \f[I]esc1\f[R] to \f[I]esc2\f[R]
 182 (e.g.\ \f[B]\[rs]x00-x1F\f[R])
 183 .TP
 184 \f[B]\[rs]\f[R]\f[I]esc1\f[R]\f[B],\f[R]\f[I]esc2\f[R]
 185 Any one of the given escape sequences or ranges \f[I]esc1\f[R] or
 186 \f[I]esc2\f[R] (e.g.\ \f[B]\[rs]r,n,x01-x04\f[R])
 187 .TP
 188 \f[B]\[rs]N\f[R]
 189 A special escape that matches a \[lq]nodent\[rq]: one or more newlines
 190 followed by the same indentation that occurs on the current line.
 191 .TP
 192 \f[B]\[rs]C\f[R]
 193 A special escape that always matches the empty string and replaces it
 194 with the indentation of the line on which it matched.
 195 For example, this pattern would match Bash-style heredocs that start
 196 with \[lq]<<-FOO\[rq] and end with a line containing only the starting
 197 indentation and the string \[lq]FOO\[rq]: \f[B]\[dq]<<-\[dq]
 198 \[at]end=(\[rs]C id) ..%\[rs]n (\[ha]end$)\f[R]
 199 .TP
 200 \f[B]\[rs]i\f[R]
 201 An identifier character (e.g.\ alphanumeric characters or underscores).
 202 .TP
 203 \f[B]\[rs]I\f[R]
 204 An identifier character, not including numbers (e.g.\ alphabetic
 205 characters or underscores).
 206 .TP
 207 \f[B]|\f[R]
 208 A word boundary (i.e.\ the edge of a word).
 209 .TP
 210 \f[B]\[rs]b\f[R]
 211 Alias for \f[B]|\f[R] (word boundary)
 212 .TP
 213 \f[B](\f[R] \f[I]pat\f[R] \f[B])\f[R]
 214 Parentheses can be used to delineate patterns, as in most languages.
 215 .TP
 216 \f[B]!\f[R] \f[I]pat\f[R]
 217 Not \f[I]pat\f[R] (don\[cq]t match if \f[I]pat\f[R] matches here)
 218 .TP
 219 \f[B][\f[R] \f[I]pat\f[R] \f[B]]\f[R]
 220 Maybe \f[I]pat\f[R] (match zero or one occurrences of \f[I]pat\f[R])
 221 .TP
 222 \f[I]N\f[R] \f[I]pat\f[R]
 223 Exactly \f[I]N\f[R] repetitions of \f[I]pat\f[R] (e.g.\ \f[B]5
 224 \[dq]x\[dq]\f[R] matches \f[B]\[lq]xxxxx\[rq]\f[R])
 225 .TP
 226 \f[I]N\f[R] \f[B]-\f[R] \f[I]M\f[R] \f[I]pat\f[R]
 227 Between \f[I]N\f[R] and \f[I]M\f[R] repetitions of \f[I]pat\f[R]
 228 (e.g.\ \f[B]2-3 \[dq]x\[dq]\f[R] matches \f[B]\[lq]xx\[rq]\f[R] or
 229 \f[B]\[lq]xxx\[rq]\f[R])
 230 .TP
 231 \f[I]N\f[R]\f[B]+\f[R] \f[I]pat\f[R]
 232 At least \f[I]N\f[R] or more repetitions of \f[I]pat\f[R] (e.g.\ \f[B]2+
 233 \[dq]x\[dq]\f[R] matches \f[B]\[lq]xx\[rq]\f[R],
 234 \f[B]\[lq]xxx\[rq]\f[R], \f[B]\[lq]xxxx\[rq]\f[R], etc.)
 235 .TP
 236 \f[B]*\f[R] \f[I]pat\f[R]
 237 Any \f[I]pat\f[R]s (zero or more, e.g.\ \f[B]* \[dq]x\[dq]\f[R] matches
 238 \f[B]\[lq]\[lq]\f[R], \f[B]\[rq]x\[rq]\f[R], \f[B]\[lq]xx\[rq]\f[R],
 239 etc.)
 240 .TP
 241 \f[B]+\f[R] \f[I]pat\f[R]
 242 Some \f[I]pat\f[R]s (one or more, e.g.\ \f[B]+ \[dq]x\[dq]\f[R] matches
 243 \f[B]\[lq]x\[rq]\f[R], \f[B]\[lq]xx\[rq]\f[R], \f[B]\[lq]xxx\[rq]\f[R],
 244 etc.)
 245 .TP
 246 \f[I]repeating-pat\f[R] \f[B]%\f[R] \f[I]sep\f[R]
 247 \f[I]repeating-pat\f[R] (see the examples above) separated by
 248 \f[I]sep\f[R] (e.g.\ \f[B]*word % \[dq],\[dq]\f[R] matches zero or more
 249 comma-separated words)
 250 .TP
 251 \f[B]..\f[R] \f[I]pat\f[R]
 252 Any text (except newlines) up to and including \f[I]pat\f[R].
 253 This is a non-greedy match and does not span newlines.
 254 .TP
 255 \f[B].. %\f[R] \f[I]skip\f[R] \f[I]pat\f[R]
 256 Any text (except newlines) up to and including \f[I]pat\f[R], skipping
 257 over instances of \f[I]skip\f[R] (e.g.\ \f[B]\[aq]\[dq]\[aq]
 258 \&..%(\[aq]\[rs]\[aq] .)
 259 \[aq]\[dq]\[aq]\f[R] opening quote, up to closing quote, skipping over
 260 backslash followed by a single character).
 261 A useful application of the \f[B]%\f[R] operator is to skip over
 262 newlines to perform multi-line matches, e.g.\ \f[B]pat1 ..%\[rs]n
 263 pat2\f[R]
 264 .TP
 265 \f[B].. =\f[R] \f[I]only\f[R] \f[I]pat\f[R]
 266 Any number of repetitions of the pattern \f[I]only\f[R] up to and
 267 including \f[I]pat\f[R] (e.g.\ \f[B]\[dq]f\[dq] ..=abc \[dq]k\[dq]\f[R]
 268 matches the letter \[lq]f\[rq] followed by some alphabetic characters
 269 and then a \[lq]k\[rq], which would match \[lq]fork\[rq], but not
 270 \[lq]free kit\[rq]) This is essentially a \[lq]non-greedy\[rq] version
 271 of \f[B]*\f[R], and \f[B]..
 272 pat\f[R] can be thought of as the special case of \f[B]..=.
 273 pat\f[R]
 274 .TP
 275 \f[B]<\f[R] \f[I]pat\f[R]
 276 Matches at the current position if \f[I]pat\f[R] matches immediately
 277 before the current position (lookbehind).
 278 \f[B]Note:\f[R] For fixed-length lookbehinds, this is quite efficient
 279 (e.g.\ \f[B]<(100 \[dq]x\[dq])\f[R]), however this can cause performance
 280 problems with variable-length lookbehinds (e.g.\ \f[B]<(\[dq]x\[dq]
 281 0-100\[dq]y\[dq])\f[R]).
 282 Also, patterns like \f[B]\[ha]\f[R], \f[B]\[ha]\[ha]\f[R], \f[B]$\f[R],
 283 and \f[B]$$\f[R] that match against line/file edges will match against
 284 the edge of the lookbehind window, so they should generally be avoided
 285 in lookbehinds.
 286 .TP
 287 \f[B]>\f[R] \f[I]pat\f[R]
 288 Matches \f[I]pat\f[R], but does not consume any input (lookahead).
 289 .TP
 290 \f[B]\[at]\f[R] \f[I]pat\f[R]
 291 Capture \f[I]pat\f[R].
 292 Captured patterns can be used in replacements.
 293 .TP
 294 \f[B]foo\f[R]
 295 The named pattern whose name is \f[B]\[lq]foo\[rq]\f[R].
 296 Pattern names come from definitions in grammar files or from named
 297 captures.
 298 Pattern names may contain dashes (\f[B]-\f[R]), but not underscores
 299 (\f[B]_\f[R]), since the underscore is used to match whitespace.
 300 See the \f[B]GRAMMAR FILES\f[R] section for more info.
 301 .TP
 302 \f[B]\[at]\f[R] \f[I]name\f[R] \f[B]:\f[R] \f[I]pat\f[R]
 303 For the rest of the current chain, define \f[I]name\f[R] to match
 304 whatever \f[I]pat\f[R] matches, i.e.\ a backreference.
 305 For example, \f[B]\[at]my-word:word \[ga]( my-word \[ga])\f[R] (matches
 306 \f[B]\[lq]asdf(asdf)\[rq]\f[R] or \f[B]\[lq]baz(baz)\[rq]\f[R], but not
 307 \f[B]\[lq]foo(baz)\[rq]\f[R])
 308 .TP
 309 \f[B]\[at]\f[R] \f[I]name\f[R] \f[B]=\f[R] \f[I]pat\f[R]
 310 Let \f[I]name\f[R] equal \f[I]pat\f[R] (named capture).
 311 Named captures can be used in text replacements.
 312 .TP
 313 \f[I]pat\f[R] \f[B]=>\f[R] \f[B]\[dq]\f[R]\f[I]replacement\f[R]\f[B]\[dq]\f[R]
 314 Replace \f[I]pat\f[R] with \f[I]replacement\f[R].
 315 Note: \f[I]replacement\f[R] should be a string (single or double
 316 quoted), and it may contain escape sequences (e.g.\ \f[B]\[rs]n\f[R]) or
 317 references to captured values: \f[B]\[at]0\f[R] (the whole of
 318 \f[I]pat\f[R]), \f[B]\[at]1\f[R] (the first capture in \f[I]pat\f[R]),
 319 \f[B]\[at]\f[R]\f[I]foo\f[R] (the capture named \f[I]foo\f[R] in
 320 \f[I]pat\f[R]), etc.
 321 For example, \f[B]\[at]word _ \[at]rest=(*word % _) =>
 322 \[dq]\[at]rest:\[rs]n\[rs]t\[at]1\[dq]\f[R] matches a word followed by
 323 whitespace, followed by a series of words and replaces it with the
 324 series of words, a colon, a newline, a tab, and then the first word.
 325 .TP
 326 \f[I]pat1\f[R] \f[B]\[ti]\f[R] \f[I]pat2\f[R]
 327 Matches when \f[I]pat1\f[R] matches and \f[I]pat2\f[R] can be found
 328 within the text of that match.
 329 (e.g.\ \f[B]comment \[ti] \[dq]TODO\[dq]\f[R] matches comments that
 330 contain \f[B]\[lq]TODO\[rq]\f[R])
 331 .TP
 332 \f[I]pat1\f[R] \f[B]!\[ti]\f[R] \f[I]pat2\f[R]
 333 Matches when \f[I]pat1\f[R] matches, but \f[I]pat2\f[R] can not be found
 334 within the text of that match.
 335 (e.g.\ \f[B]comment \[ti] \[dq]IGNORE\[dq]\f[R] matches only comments
 336 that do not contain \f[B]\[lq]IGNORE\[rq]\f[R])
 337 .TP
 338 \f[I]name\f[R]\f[B]:\f[R] \f[I]pat1\f[R]; \f[I]pat2\f[R]
 339 Define \f[I]name\f[R] to mean \f[I]pat1\f[R] (pattern definition) inside
 340 the pattern \f[I]pat2\f[R].
 341 For example, a recursive pattern can be defined and used like this:
 342 \f[B]paren-comment: \[dq](*\[dq] ..%paren-comment \[dq]*)\[dq];
 343 paren-comment\f[R]
 344 .TP
 345 \f[B]\[at]:\f[R]\f[I]name\f[R] \f[B]=\f[R] \f[I]pat\f[R]
 346 Match \f[I]pat\f[R] and tag it with the given name as metadata.
 347 .TP
 348 \f[I]name\f[R]\f[B]::\f[R] \f[I]pat\f[R]
 349 Syntactic sugar for \f[I]name\f[R]\f[B]:\f[R]
 350 \f[B]\[at]:\f[R]\f[I]name\f[R]\f[B]=\f[R]\f[I]pat\f[R] (define a pattern
 351 that also attaches a metadata tag of the same name)
 352 .TP
 353 \f[B]#\f[R] \f[I]comment\f[R]
 354 A line comment, ignored by BP
 355 .SH GRAMMAR FILES
 356 \f[B]bp\f[R] allows loading extra grammar files, which define patterns
 357 which may be used for matching.
 358 The \f[B]builtins\f[R] grammar file is loaded by default, and it defines
 359 a few useful general-purpose patterns.
 360 For example, it defines the \f[B]parens\f[R] rule, which matches pairs
 361 of matching parentheses, accounting for nested inner parentheses:
 362 .RS
 363 .PP
 364 \f[B]bp \[aq]my_func{parens}\[aq]\f[R]
 365 .RE
 366 .PP
 367 BP\[cq]s builtin grammar file defines a few other commonly used patterns
 368 such as:
 369 .IP \[bu] 2
 370 \f[B]braces\f[R] (matching \f[B]{}\f[R] pairs), \f[B]brackets\f[R]
 371 (matching \f[B][]\f[R] pairs), \f[B]anglebraces\f[R] (matching
 372 \f[B]<>\f[R] pairs)
 373 .IP \[bu] 2
 374 \f[B]string\f[R]: a single- or double-quote delimited string, including
 375 standard escape sequences
 376 .IP \[bu] 2
 377 \f[B]id\f[R] or \f[B]var\f[R]: an identifier (full UTF-8 support)
 378 .IP \[bu] 2
 379 \f[B]word\f[R]: similar to \f[B]id\f[R]/\f[B]var\f[R], but can start
 380 with a number
 381 .IP \[bu] 2
 382 \f[B]Hex\f[R], \f[B]hex\f[R], \f[B]HEX\f[R]: a mixed-case, lowercase, or
 383 uppercase hex digit
 384 .IP \[bu] 2
 385 \f[B]digit\f[R]: a digit from 0-9
 386 .IP \[bu] 2
 387 \f[B]int\f[R]: one or more digits
 388 .IP \[bu] 2
 389 \f[B]number\f[R]: an int or floating point literal
 390 .IP \[bu] 2
 391 \f[B]esc\f[R], \f[B]tab\f[R], \f[B]nl\f[R], \f[B]cr\f[R],
 392 \f[B]crlf\f[R], \f[B]lf\f[R]: Shorthand for escape sequences
 393 .PP
 394 \f[B]bp\f[R] also comes with a few grammar files for common programming
 395 languages, which may be loaded on demand.
 396 These grammar files are not comprehensive syntax definitions, but only
 397 some common patterns.
 398 For example, the c++ grammar file contains definitions for
 399 \f[B]//\f[R]-style line comments as well as \f[B]/*...*/\f[R]-style
 400 block comments.
 401 Thus, you can find all comments with the word \[lq]TODO\[rq] with the
 402 following command:
 403 .RS
 404 .PP
 405 \f[B]bp -g c++ \[aq]{comment \[ti] \[dq]TODO\[dq]}\[aq] *.cpp\f[R]
 406 .RE
 407 .SH EXAMPLES
 408 Find files containing the literal string \[lq]foo.baz\[rq] (a string
 409 pattern):
 410 .RS
 411 .PP
 412 \f[B]ls | bp foo.baz\f[R]
 413 .RE
 414 .PP
 415 Find files ending with \[lq].c\[rq] and print the name with the
 416 \[lq].c\[rq] replaced with \[lq].h\[rq]:
 417 .RS
 418 .PP
 419 \f[B]ls | bp \[aq].c{$}\[aq] -r \[aq].h\[aq]\f[R]
 420 .RE
 421 .PP
 422 Find the word \[lq]foobar\[rq], followed by a pair of matching
 423 parentheses in the file \f[I]my_file.py\f[R]:
 424 .RS
 425 .PP
 426 \f[B]bp \[aq]foobar{parens}\[aq] my_file.py\f[R]
 427 .RE
 428 .PP
 429 Using the \f[I]html\f[R] grammar, find all \f[I]element\f[R]s matching
 430 the tag \f[I]a\f[R] in the file \f[I]foo.html\f[R]:
 431 .RS
 432 .PP
 433 \f[B]bp -g html \[aq]{element \[ti] (\[ha]\[ha]\[dq]<a \[dq])}\[aq]
 434 foo.html\f[R]
 435 .RE
 436 .SH AUTHORS
 437 Bruce Hill (\f[I]bruce\[at]bruce-hill.com\f[R]).