fgrep - Linux Command

Transcription

1 f - CetOS Liux Users Guide f f - Liux Commad SYNOPSIS [optios] PATTE RN [FI LE...] [ optios ] [ -e -f FILE ] [ FILE...] DESCRIPTION Grep searches the amed iput FILE s (or stadard iput if o files are amed or the file ame - is give) for lies cotaiig a match to the give. By default prits the matchig lies. I additio two variat programs e ad f are available. E is the same as -E. F is the same as -F. 1 / 14

2 f - CetOS Liux Users Guide OPTIONS -A --after-cotext= Prit lies of trailig cotext after matchig lies. -- betwee cotiguous groups of matches. -a --text Process a biary file as if it were text; this is equivalet to Places a lie cotaiig --biary-files=text optio. -B --before-cotext= Prit lies of leadig cotext before matchig lies. Places a lie cotaiig -- betwee cotiguous groups of matches. -C --cotext= Prit lies of output cotext. Places a lie cotaiig -- betwee cotiguous groups of matches. -b --byte-offset Prit the byte offset withi the iput file before each lie of output. --biary-files= TYPE If the first few bytes of a file idicate that the file cotais biary data assume that the file is of type the 2 / 14

3 f - CetOS Liux Users Guide TYPE. By default TYPE is biary ad ormally outputs either a oe-lie mes- sage sayig that a biary file matches or o message if there is o match. If TYPE is without-match assumes that a biary file does ot match; this is equivalet to the -I optio. If TYPE is text processes a biary file as if it were text; this is equivalet to the -a optio. Warig: --biary-files=text might output biary garbage which ca have asty side effects if the output is a termial ad if the termi- al driver iterprets some of it as commads. --colour[= WHEN ] --color[= WHEN ] Surroud the matchig strig with the marker fid i GREP_COLOR eviromet variable. WHEN may be â everâ â alwaysâ or â autoâ just as if they were ordiary files. If ACTION is skip direc- tories are siletly skipped. If 3 / 14

4 f - CetOS Liux Users Guide ACTION is recurse reads all files uder each directory recursively; this is equivalet to the -r optio. -E --exteded-regexp Iterpret as a exteded regular expressio (see below). -e --regexp= Use as the patter; useful to protect patters begiig with -. -F --fixed-strigs Iterpret as a list of fixed strigs separated by ew- lies ay of which is to be matched. -P --perl-regexp Iterpret as a Perl regular expressio. -f FILE --file= FILE Obtai patters from FILE oe per lie. The empty file co- tais zero patters ad therefore matches othig. -G 4 / 14

5 f - CetOS Liux Users Guide --basic-regexp Iterpret as a basic regular expressio (see below). -H --with-fileame Prit the fileame for each match. -h --o-fileame This is the default. Suppress the prefixig of fileames o output whe multiple files are searched. --help Output a brief help message. -I Process a biary file as if it did ot cotai matchig data; this is equivalet to the --biary-files=without-match optio. -i --igore-case Igore case distictios i both the ad the iput files. -L --files-without-match Suppress ormal output; istead prit the ame of each iput file from which o output would ormally have bee prited. The scaig will stop o the first match. -l --files-with-matches Suppress ormal output; istead prit the ame of each iput file from which output would ormally have bee prited. The scaig will stop o the first match. of the default read(2) system call. I some situatios --mmap yields better performace. However --mmap ca cause udefied behavior (icludig core dumps) if a iput file shriks while 5 / 14

6 f - CetOS Liux Users Guide is operatig or if a I/O error occurs. - --lie-umber Prefix each lie of output with the lie umber withi its iput -o --oly-matchig Show oly the part of a matchig lie that matches. file. --label= LABEL Displays iput actually comig from stadard iput as iput com- ig from file LABEL. This is especially useful for tools like gzip -cd foo.gz --label=foo somethig z e.g. --lie-buffered Use lie bufferig it ca be a performace peality. -q --quiet --silet Quiet; do ot write aythig to stadard output. Exit immedi- status if ay match is foud eve if a error -s or --o-messages optio. -R -r --recursive -d recurse optio. Read all files uder each directory recursively; this is equiv- ately with zero was detected. Also see the alet to the 6 / 14

7 f - CetOS Liux Users Guide --iclude=. --exclude=. Recurse i directories oly searchig file matchig Recurse i directories skip file matchig -s --o-messages Suppress error messages about oexistet or ureadable files. ote: ulike GNU traditioal did ot co- form to POSIX.2 because traditioal lacked a -q optio ad its -s optio behaved like GNU â s -q optio. Shell scripts iteded to be portable to traditioal should avoid both -q ad -s ad should redirect output to /dev/ull istead. -U --biary Treat the file(s) as biary. By default uder MS-DOS ad MS Portability Widows guesses the file type by lookig at the cotets of the first 32KB read from the file. If decides the file is a text file it strips the CR characters from the origial file cotets (to make regular expressios with ^ ad $ work correctly). Specifyig 7 / 14

8 f - CetOS Liux Users Guide -U overrules this guesswork causig all files to be read ad passed to the matchig mechaism verbatim; if the file is a text file with CR/LF pairs at the ed of each sio umber should be icluded i all bug reports (see below). -v --ivert-match Ivert the sese of matchig to select o-matchig lies. -w --word-regexp Select oly those lies cotaiig matches that form whole words. The test is that the matchig substrig must either be at the begiig of the lie or preceded by a o-word co- stituet character. Similarly it must be either at the ed of the lie or followed by a o-word costituet character. Wordcostituet characters are letters digits ad the uderscore. -x --lie-regexp Select oly those matches that exactly match the whole lie. -y Obsolete syoym for -i. -Z --ull Output a zero byte (the ASCII NUL character) istead of the character that ormally follows a file ame. For example -lz outputs a zero byte after each file ame istead of the usual ewlie. This optio makes the output uambiguous eve i the presece of file ames cotaiig uusual characters like ewlies. This optio ca be used with commads like fid -prit0 perl -0 sort -z ad 8 / 14

9 f - CetOS Liux Users Guide xargs -0 to process arbitrary file ames eve those that cotai ewlie characters. REGULAR EXPRESSIONS A regular expressio is a patter that describes a set of strigs. Regular expressios are costructed aalogously to arithmetic expres- sios by usig various operators to combie smaller expressios. Grep uderstads two differet versios of regular expressio sytax: â œbasicâ ad â œexteded.â I GNU there is o differece i avail- able fuctioality usig either sytax. I other implemetatios basic regular expressios are less powerful. The followig descriptio applies to exteded regular expressios; differeces for basic regular expressios are summarized afterwards. The fudametal buildig blocks are the regular expressios that match a sigle character. Most characters icludig all letters ad digits are regular expressios that match themselves. Ay metacharacter with special meaig may be quoted by precedig it with a backslash. A bracket expressio is a list of characters eclosed by [ ad ]. It matches ay sigle character i that list; if the first character of the list is the caret ^ the it matches ay character ot i the list. For example the regular expressio [ ] matches ay sigle digit. Withi a bracket expressio a rage expressio cosists of two charac- depeds upo the C locale ad the ASCII character ecodig whereas the former is idepedet of locale ad character set. (Note that the brackets i these class ames are part of the symbolic ames ad must be icluded i additio to the brackets delimitig the bracket list.) Most metacharacters lose their special meaig iside lists. To iclude a literal ] place it first i the list. Similarly to iclude a literal ^ place it aywhere but first. Fially to iclude a literal 9 / 14

10 f - CetOS Liux Users Guide - place it last. The period. matches ay sigle character. The symbol w is a syoym for [[:alum:]] ad W is a syoym for [^[:alum]]. The caret ^ ad the dollar sig $ are metacharacters that respectively match the empty strig at the begiig ad ed of a lie. The symbols < ad > respectively match the empty strig at the begiig ad ed of a word. The symbol b matches the empty strig at the edge of a word ad B matches the empty strig provided itâ s ot at the edge of a word. A regular expressio may be followed by oe of several repetitio oper- ators:? The precedig item is optioal ad matched at most oce. * The precedig item will be matched zero or more times. + The precedig item will be matched oe or more times. } The precedig item is matched exactly times. } The precedig item is matched or more times. 10 / 14

11 f - CetOS Liux Users Guide m } The precedig item is matched at least times but ot more tha m times. Two regular expressios may be cocateated; the resultig regular expressio matches ay strig formed by cocateatig two substrigs that respectively match the cocateated subexpressios. Two regular expressios may be joied by the ifix operator ; the resultig regular expressio matches ay strig matchig either subex- pressio. Repetitio takes precedece over cocateatio which i tur takes precedece over alteratio. A whole subexpressio may be eclosed i paretheses to override these precedece rules. The backreferece where is a sigle digit matches the substrig previously matched by the th parethesized subexpressio of the regu- lar expressio. I basic regular expressios the metacharacters? + ( ad ) lose their special meaig; istead use the backslashed versios? + ( 11 / 14

12 f - CetOS Liux Users Guide ad ). Traditioal e did ot support the metacharacter ad some e implemetatios support istead so portable scripts should avoid i e patters ad should use [] to match a literal. ot set but LC_MESSAGES is set to pt_br the Brazilia Portuguese is used for the LC_MESSAGES locale. The C locale is used if oe of these eviromet variables are set or if the locale catalog is ot istalled or if was ot compiled with atioal laguage support (NLS). GREP_OPTIONS This variable specifies default optios to be placed i frot of optios. For example if GREP_OPTIONS is â â --biary-files=without-match --directories=skip â â behaves as if the two optios --biary-files=without-match ad --direc- ay explicit 12 / 14

13 f - CetOS Liux Users Guide tories=skip had bee specified before ay explicit optios. Optio specificatios are separated by whitespace. A backslash escapes the ext character so it ca be used to specify a optio cotaiig whitespace or a backslash. GREP_COLOR Specifies the marker for highlightig. LC_ALL LC_COLLATE LANG These variables specify the LC_COLLATE locale which determies the collatig sequece used to iterpret rage expressios like [a-z]. LC_ALL LC_CTYPE LANG These variables specify the LC_CTYPE locale which determies the type of characters e.g. which characters are whitespace. LC_ALL LC_MESSAGES LANG These variables specify the LC_MESSAGES locale which determies the laguage that uses for messages. The default C locale uses America Eglish messages. POSIXLY_CORRECT If set behaves as POSIX.2 requires; otherwise behaves more like other GNU programs. POSIX.2 requires that optios that follow file ames must be treated as file ames; by default such optios are permuted to the frot of the operad list ad are treated as optios. Also POSIX.2 requires that urecogized optios be diagosed as â œillegalâ but sice they 13 / 14

14 f - CetOS Liux Users Guide are ot really agaist the law the default is to diagose them as â œivalidâ. POSIXLY_CORRECT also disables _ N _GNU_ooptio_argv_flags_ described below. _ N _GNU_ooptio_argv_flags_ (Here N is â s umeric process ID.) If the i th character of this eviromet variableâ s value is 1 do ot cosider the i th operad of to be a optio eve if it appears to be oe. A shell ca put this variable i the eviromet for each com- mad it rus specifyig which operads are the results of file ame wildcard expasio ad therefore should ot be treated as optios. This behavior is available oly with the GNU C Backrefereces are very slow ad may require expoetial time. GNU Project 2002/01/22 GREP(1) Liux Help documets. These maual pages will also work for Red Hat 5.2 Ma(1) output coverted with ma2html Joomla SEO powered by JoomSEF 14 / 14