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diff --git a/gnu/usr.bin/grep/grep.1 b/gnu/usr.bin/grep/grep.1 index 57093b6..3b957a0 100644 --- a/gnu/usr.bin/grep/grep.1 +++ b/gnu/usr.bin/grep/grep.1 @@ -1,234 +1,477 @@ -.TH GREP 1 "1988 December 13" "GNU Project" \" -*- nroff -*- -.UC 4 +.\" grep man page +.de Id +.ds Dt \\$4 +.. +.Id $Id: grep.1,v 1.1 1998/11/22 06:45:20 alainm Exp $ +.TH GREP 1 \*(Dt "GNU Project" .SH NAME -grep, egrep \- print lines matching a regular expression +grep, egrep, fgrep \- print lines matching a pattern .SH SYNOPSIS .B grep -[ -.B \-CVbchilnsvwx -] [ -.BI \- num -] [ -.B \-AB -.I num -] [ [ -.B \-e -] -.I expr -| -.B \-f -.I file -] [ -.I "files ..." -] +[-[AB] NUM] [-CEFGVabchiLlnqrsvwxyUu] [-e PATTERN | -f FILE] +[-d ACTION] [--directories=ACTION] +[--extended-regexp] [--fixed-strings] [--basic-regexp] +[--regexp=PATTERN] [--file=FILE] [--ignore-case] [--word-regexp] +[--line-regexp] [--line-regexp] [--no-messages] [--revert-match] +[--version] [--help] [--byte-offset] [--line-number] +[--with-filename] [--no-filename] [--quiet] [--silent] [--text] +[--files-without-match] [--files-with-matcces] [--count] +[--before-context=NUM] [--after-context=NUM] [--context] +[--binary] [--unix-byte-offsets] [--recursive] +.I files... .SH DESCRIPTION -.I Grep -searches the files listed in the arguments (or standard -input if no files are given) for all lines that contain a match for -the given -.IR expr . -If any lines match, they are printed. -.PP -Also, if any matches were found, -.I grep -exits with a status of 0, but if no matches were found it exits -with a status of 1. This is useful for building shell scripts that -use -.I grep -as a condition for, for example, the -.I if -statement. -.PP -When invoked as -.I egrep -the syntax of the -.I expr -is slightly different; See below. -.br -.SH "REGULAR EXPRESSIONS" -.RS 2.5i -.ta 1i 2i -.sp -.ti -2.0i -(grep) (egrep) (explanation) -.sp -.ti -2.0i -\fIc\fP \fIc\fP a single (non-meta) character matches itself. -.sp -.ti -2.0i -\&. . matches any single character except newline. -.sp -.ti -2.0i -\\? ? postfix operator; preceeding item is optional. -.sp -.ti -2.0i -\(** \(** postfix operator; preceeding item 0 or -more times. -.sp -.ti -2.0i -\\+ + postfix operator; preceeding item 1 or -more times. -.sp -.ti -2.0i -\\| | infix operator; matches either -argument. -.sp -.ti -2.0i -^ ^ matches the empty string at the beginning of a line. -.sp -.ti -2.0i -$ $ matches the empty string at the end of a line. -.sp -.ti -2.0i -\\< \\< matches the empty string at the beginning of a word. -.sp -.ti -2.0i -\\> \\> matches the empty string at the end of a word. -.sp -.ti -2.0i -[\fIchars\fP] [\fIchars\fP] match any character in the given class; if the -first character after [ is ^, match any character -not in the given class; a range of characters may -be specified by \fIfirst\-last\fP; for example, \\W -(below) is equivalent to the class [^A\-Za\-z0\-9] -.sp -.ti -2.0i -\\( \\) ( ) parentheses are used to override operator precedence. -.sp -.ti -2.0i -\\\fIdigit\fP \\\fIdigit\fP \\\fIn\fP matches a repeat of the text -matched earlier in the regexp by the subexpression inside the nth -opening parenthesis. -.sp -.ti -2.0i -\\ \\ any special character may be preceded -by a backslash to match it literally. -.sp -.ti -2.0i -(the following are for compatibility with GNU Emacs) -.sp -.ti -2.0i -\\b \\b matches the empty string at the edge of a word. -.sp -.ti -2.0i -\\B \\B matches the empty string if not at the edge of a word. -.sp -.ti -2.0i -\\w \\w matches word-constituent characters (letters & digits). -.sp -.ti -2.0i -\\W \\W matches characters that are not word-constituent. -.RE -.PP -Operator precedence is (highest to lowest) ?, \(**, and +, concatenation, -and finally |. All other constructs are syntactically identical to -normal characters. For the truly interested, the file dfa.c describes -(and implements) the exact grammar understood by the parser. -.SH OPTIONS -.TP -.BI \-A " num" -print <num> lines of context after every matching line -.TP -.BI \-B " num" -print -.I num -lines of context before every matching line -.TP -.B \-C -print 2 lines of context on each side of every match -.TP -.BI \- num -print -.I num -lines of context on each side of every match -.TP -.B \-V -print the version number on the diagnostic output +.PP +.B Grep +searches the named input +.I files +(or standard input if no files are named, or +the file name +.B \- +is given) +for lines containing a match to the given +.IR pattern . +By default, +.B grep +prints the matching lines. +.PP +There are three major variants of +.BR grep , +controlled by the following options. +.PD 0 .TP -.B \-b -print every match preceded by its byte offset +.B \-G, --basic-regexp +Interpret +.I pattern +as a basic regular expression (see below). This is the default. +.TP +.B \-E, --extended-regexp +Interpret +.I pattern +as an extended regular expression (see below). +.TP +.B \-F, --fixed-strings +Interpret +.I pattern +as a list of fixed strings, separated by newlines, +any of which is to be matched. +.LP +In addition, two variant programs +.B egrep +and +.B fgrep +are available. +.B Egrep +is similar (but not identical) to +.BR "grep\ \-E" , +and is compatible with the historical Unix +.BR egrep . +.B Fgrep +is the same as +.BR "grep\ \-F" . +.PD +.LP +All variants of +.B grep +understand the following options: +.PD 0 +.TP +.BI \-A " NUM" ", --after-context=" NUM +Print +.I NUM +lines of trailing context after matching lines. +.TP +.BI \-B " NUM" ", --before-context=" NUM +Print +.I NUM +lines of leading context before matching lines. +.TP +.BI \-C ,\ --context"[=NUM]" +Print +.I NUM +lines (default 2) of output context. .TP -.B \-c -print a total count of matching lines only +.BI \- NUM \ +Same as --context=NUM lines of leading and trailing context. However, +.B grep +will never print any given line more than once. +.TP +.B \-V, --version +Print the version number of +.B grep +to standard error. This version number should +be included in all bug reports (see below). .TP -.BI \-e " expr" -search for -.IR expr ; -useful if -.I expr -begins with \- +.B \-b, --byte-offset +Print the byte offset within the input file before +each line of output. .TP -.BI \-f " file" -search for the expression contained in -.I file +.B \-c, --count +Suppress normal output; instead print a count of +matching lines for each input file. +With the +.B \-v, --revert-match +option (see below), count non-matching lines. .TP -.B \-h -don't display filenames on matches +.BI \-d " ACTION" ", --directories=" ACTION +If an input file is a directory, use +.I ACTION +to process it. By default, +.I ACTION +is +.BR read , +which means that directories are read just as if they were ordinary files. +If +.I ACTION +is +.BR skip , +directories are silently skipped. +If +.I ACTION +is +.BR recurse , +.B +grep reads all files under each directory, recursively; +this is equivalent to the +.B \-r +option. .TP -.B \-i -ignore case difference when comparing strings +.BI \-e " PATTERN" ", --regexp=" PATTERN +Use +.I PATTERN +as the pattern; useful to protect patterns beginning with +.BR \- . .TP -.B \-l -list files containing matches only +.BI \-f " FILE" ", --file=" FILE +Obtain patterns from +.IR FILE , +one per line. +The empty file contains zero patterns, and therfore matches nothing. .TP -.B \-n -print each match preceded by its line number +.B \-h, --no-filename +Suppress the prefixing of filenames on output +when multiple files are searched. .TP +.B \-i, --ignore-case +Ignore case distinctions in both the +.I pattern +and the input files. +.TP +.B \-L, --files-without-match +Suppress normal output; instead print the name +of each input file from which no output would +normally have been printed. The scanning will stop +on the first match. +.TP +.B \-l, --files-with-matches +Suppress normal output; instead print +the name of each input file from which output +would normally have been printed. The scanning will +stop on the first match. +.TP +.B \-n, --line-number +Prefix each line of output with the line number +within its input file. +.TP +.B \-q, --quiet, --silent +Quiet; suppress normal output. The scanning will stop +on the first match. +Also see the .B \-s -run silently producing no output except error messages +or +.B --no-messages +option below. .TP -.B \-v -print only lines that contain no matches for the <expr> +.B \-r, --recursive +Read all files under each directory, recursively; +this is equivalent to the +.B "\-d recurse" +option. +.TP +.B \-s, --no-messages +Suppress error messages about nonexistent or unreadable files. +Portability note: unlike GNU +.BR grep , +BSD +.B grep +does not comply with POSIX.2, because BSD +.B grep +lacks a +.B \-q +option and its +.B \-s +option behaves like GNU +.BR grep 's +.B \-q +option. +Shell scripts intended to be portable to BSD +.B grep +should avoid both +.B \-q +and +.B \-s +and should redirect output to /dev/null instead. +.TP +.B \-a, --text +Do not suppress output lines that contain binary data. +Normally, if the first few bytes of a file indicate that +the file contains binary data, +.B grep +outputs only a message saying that the file matches the pattern. +This option causes +.B grep +to act as if the file is a text file, +even if it would otherwise be treated as binary. +.TP +.B \-v, --revert-match +Invert the sense of matching, to select non-matching lines. +.TP +.B \-w, --word-regexp +Select only those lines containing matches that form whole words. +The test is that the matching substring must either be at the +beginning of the line, or preceded by a non-word constituent +character. Similarly, it must be either at the end of the line +or followed by a non-word constituent character. Word-constituent +characters are letters, digits, and the underscore. +.TP +.B \-x, --line-regexp +Select only those matches that exactly match the whole line. .TP -.B \-w -print only lines where the match is a complete word +.B \-y +Obsolete synonym for +.BR \-i . .TP -.B \-x -print only lines where the match is a whole line -.SH "SEE ALSO" -emacs(1), ed(1), sh(1), -.I "GNU Emacs Manual" -.SH INCOMPATIBILITIES -The following incompatibilities with UNIX -.I grep -exist: +.B \-U, --binary +Treat the file(s) as binary. By default, under MS-DOS and MS-Windows, +.BR grep +guesses the file type by looking at the contents of the first 32KB +read from the file. If +.BR grep +decides the file is a text file, it strips the CR characters from the +original file contents (to make regular expressions with +.B ^ +and +.B $ +work correctly). Specifying +.B \-U +overrules this guesswork, causing all files to be read and passed to the +matching mechanism verbatim; if the file is a text file with CR/LF +pairs at the end of each line, this will cause some regular +expressions to fail. This option is only supported on MS-DOS and +MS-Windows. +.TP +.B \-u, --unix-byte-offsets +Report Unix-style byte offsets. This switch causes +.B grep +to report byte offsets as if the file were Unix-style text file, i.e. with +CR characters stripped off. This will produce results identical to running +.B grep +on a Unix machine. This option has no effect unless +.B \-b +option is also used; it is only supported on MS-DOS and MS-Windows. +.PD +.SH "REGULAR EXPRESSIONS" .PP -.RS 0.5i -The context-dependent meaning of \(** is not quite the same (grep only). +A regular expression is a pattern that describes a set of strings. +Regular expressions are constructed analogously to arithmetic +expressions, by using various operators to combine smaller expressions. .PP -.B \-b -prints a byte offset instead of a block offset. +.B Grep +understands two different versions of regular expression syntax: +``basic'' and ``extended.'' In +.RB "GNU\ " grep , +there is no difference in available functionality using either syntax. +In other implementations, basic regular expressions are less powerful. +The following description applies to extended regular expressions; +differences for basic regular expressions are summarized afterwards. .PP -The {\fIm,n\fP} construct of System V grep is not implemented. +The fundamental building blocks are the regular expressions that match +a single character. Most characters, including all letters and digits, +are regular expressions that match themselves. Any metacharacter with +special meaning may be quoted by preceding it with a backslash. .PP -.SH BUGS -GNU \fIe?grep\fP has been thoroughly debugged and tested over a period -of several years; we think it's a reliable beast or we wouldn't -distribute it. If by some fluke of the universe you discover a bug, -send a detailed description (including options, regular expressions, -and a copy of an input file that can reproduce it) to mike@ai.mit.edu. +A list of characters enclosed by +.B [ +and +.B ] +matches any single +character in that list; if the first character of the list +is the caret +.B ^ +then it matches any character +.I not +in the list. +For example, the regular expression +.B [0123456789] +matches any single digit. A range of ASCII characters +may be specified by giving the first and last characters, separated +by a hyphen. +Finally, certain named classes of characters are predefined. +Their names are self explanatory, and they are +.BR [:alnum:] , +.BR [:alpha:] , +.BR [:cntrl:] , +.BR [:digit:] , +.BR [:graph:] , +.BR [:lower:] , +.BR [:print:] , +.BR [:punct:] , +.BR [:space:] , +.BR [:upper:] , +and +.BR [:xdigit:]. +For example, +.B [[:alnum:]] +means +.BR [0-9A-Za-z] , +except the latter form is dependent upon the ASCII character encoding, +whereas the former is portable. +(Note that the brackets in these class names are part of the symbolic +names, and must be included in addition to the brackets delimiting +the bracket list.) Most metacharacters lose their special meaning +inside lists. To include a literal +.B ] +place it first in the list. Similarly, to include a literal +.B ^ +place it anywhere but first. Finally, to include a literal +.B \- +place it last. .PP -.SH AUTHORS -Mike Haertel wrote the deterministic regexp code and the bulk -of the program. +The period +.B . +matches any single character. +The symbol +.B \ew +is a synonym for +.B [[:alnum:]] +and +.B \eW +is a synonym for +.BR [^[:alnum]] . .PP -James A. Woods is responsible for the hybridized search strategy -of using Boyer-Moore-Gosper fixed-string search as a filter -before calling the general regexp matcher. +The caret +.B ^ +and the dollar sign +.B $ +are metacharacters that respectively match the empty string at the +beginning and end of a line. +The symbols +.B \e< +and +.B \e> +respectively match the empty string at the beginning and end of a word. +The symbol +.B \eb +matches the empty string at the edge of a word, +and +.B \eB +matches the empty string provided it's +.I not +at the edge of a word. .PP -Arthur David Olson contributed code that finds fixed strings for -the aforementioned BMG search for a large class of regexps. +A regular expression may be followed by one of several repetition operators: +.PD 0 +.TP +.B ? +The preceding item is optional and matched at most once. +.TP +.B * +The preceding item will be matched zero or more times. +.TP +.B + +The preceding item will be matched one or more times. +.TP +.BI { n } +The preceding item is matched exactly +.I n +times. +.TP +.BI { n ,} +The preceding item is matched +.I n +or more times. +.TP +.BI {, m } +The preceding item is optional and is matched at most +.I m +times. +.TP +.BI { n , m } +The preceding item is matched at least +.I n +times, but not more than +.I m +times. +.PD +.PP +Two regular expressions may be concatenated; the resulting +regular expression matches any string formed by concatenating +two substrings that respectively match the concatenated +subexpressions. +.PP +Two regular expressions may be joined by the infix operator +.BR | ; +the resulting regular expression matches any string matching +either subexpression. +.PP +Repetition takes precedence over concatenation, which in turn +takes precedence over alternation. A whole subexpression may be +enclosed in parentheses to override these precedence rules. .PP -Richard Stallman wrote the backtracking regexp matcher that is used -for \\\fIdigit\fP backreferences, as well as the GNU getopt. The -backtracking matcher was originally written for GNU Emacs. +The backreference +.BI \e n\c +\&, where +.I n +is a single digit, matches the substring +previously matched by the +.IR n th +parenthesized subexpression of the regular expression. .PP -D. A. Gwyn wrote the C alloca emulation that is provided so -System V machines can run this program. (Alloca is used only -by RMS' backtracking matcher, and then only rarely, so there -is no loss if your machine doesn't have a "real" alloca.) +In basic regular expressions the metacharacters +.BR ? , +.BR + , +.BR { , +.BR | , +.BR ( , +and +.BR ) +lose their special meaning; instead use the backslashed +versions +.BR \e? , +.BR \e+ , +.BR \e{ , +.BR \e| , +.BR \e( , +and +.BR \e) . .PP -Scott Anderson and Henry Spencer designed the regression tests -used in the "regress" script. +In +.B egrep +the metacharacter +.B { +loses its special meaning; instead use +.BR \e{ . +.SH DIAGNOSTICS +.PP +Normally, exit status is 0 if matches were found, +and 1 if no matches were found. (The +.B \-v +option inverts the sense of the exit status.) +Exit status is 2 if there were syntax errors +in the pattern, inaccessible input files, or +other system errors. +.SH BUGS +.PP +Email bug reports to +.BR bug-gnu-utils@gnu.org . +Be sure to include the word ``grep'' somewhere in the ``Subject:'' field. +.PP +Large repetition counts in the +.BI { m , n } +construct may cause grep to use lots of memory. +In addition, +certain other obscure regular expressions require exponential time +and space, and may cause +.B grep +to run out of memory. .PP -Paul Placeway wrote the original version of this manual page. +Backreferences are very slow, and may require exponential time. |