Grep - Revision history

Jimbo: we've been through this before - if you're n00b enough to need that example of grep, you're n00b enough to need an example of redirection as well =)

2007-08-22T22:26:33Z

we've been through this before - if you're n00b enough to need that example of grep, you're n00b enough to need an example of redirection as well =)

Gvtjongahung: cat | grep -> grep

2007-08-22T21:38:59Z

cat | grep -> grep

Jimbo: /* Producing results like find does */

2006-05-28T05:17:47Z

Producing results like find does

Jimbo at 05:17, 28 May 2006

2006-05-28T05:17:16Z

Jimbo: /* Common uses of grep */

2005-09-03T17:05:26Z

Common uses of grep

Simon: Common uses of grep

2005-01-17T17:40:49Z

Common uses of grep

Dave at 00:51, 23 December 2004

2004-12-23T00:51:40Z

Jimbo at 20:34, 25 August 2004

2004-08-25T20:34:16Z

Dave at 20:18, 25 August 2004

2004-08-25T20:18:01Z

Jimbo at 18:36, 25 August 2004

2004-08-25T18:36:39Z

New page

This page should have a description of what grep does, and some of the more common ways to use it, such as piping the results of [[ls]] or [[cat]] through it.

[[Category:FreeBSD Terminology]] [[Category:System Commands]]

@@ Line 27: / Line 27: @@
 Let's say you want to know which of your users has [[csh]] as their shell:
-  samizdata# '''grep csh /etc/passwd'''
+  samizdata# '''cat csh | grep /etc/passwd'''
   root:*:0:0:Avatar:/root:/bin/csh
   samizdata#
-Looks like only [[root]] does.
+Looks like only [[root]] does.  (You could also have used grep by itself to do the same thing - '''grep csh /etc/passwd''' - but it's important to understand and get used to the idea of redirecting output from one command to the next.)
 ==Producing results like [[find]] does==

@@ Line 27: / Line 27: @@
 Let's say you want to know which of your users has [[csh]] as their shell:
-  samizdata# '''cat passwd | grep csh'''
+  samizdata# '''grep csh /etc/passwd'''
   root:*:0:0:Avatar:/root:/bin/csh
   samizdata#

@@ Line 39: / Line 39: @@
   server# '''grep -lr PATTERN *'''
-Perhaps you wanted to '''delete''' all files in this directory and all its subdirectories which contains the word PATTERN?
+Perhaps you wanted to ''delete'' all files in this directory and all its subdirectories which contains the word PATTERN?
   server# '''grep -lr PATTERN * | [[xargs]] rm'''

@@ Line 1: / Line 1: @@
 [[grep]] returns results that match a string. You can use it to find a line in a file in a directory, by having grep run through the directory and show you what matches your query. Grep accepts input from the commandline, but is more often fed input in conjunction with other commands, such as [[find]], [[ls]] or [[cat]]:
@@ Line 31: / Line 33: @@
 Looks like only [[root]] does.
-==Common uses of grep==
+==Producing results like [[find]] does==
 '''grep -l pattern *''' to get only the filename of files that match in the current directory.

← Older revision		Revision as of 17:05, 3 September 2005
Line 38:		Line 38:

	'''grep -l goodpattern * \| grep -v badpattern ''' This use a [[Pipe]] to get grep output as the input of another grep; it gets you lines having goodpattern but not badpattern in the current directory (the "-v" means "non-matching instead of matching"). You can switch the two grep around if you like, but the directory to be searched must go to the leftmost grep after the pattern.		'''grep -l goodpattern * \| grep -v badpattern ''' This use a [[Pipe]] to get grep output as the input of another grep; it gets you lines having goodpattern but not badpattern in the current directory (the "-v" means "non-matching instead of matching"). You can switch the two grep around if you like, but the directory to be searched must go to the leftmost grep after the pattern.
		+
		+	'''grep -E "cat\|dog\|giraffe" pets.txt''' This will search the file pets.txt for any line including the patterns "cat", "dog", OR "giraffe". Very handy. Note the '''-E''' argument - that specifies an extended regular expression; the "or" pipe construct doesn't work with basic regular expressions ('''grep''''s default regexp type).

	'''grep -f No-No-list *''' to get patterns from to match from the file 'No-No-list' instead of the command line. There can be hundreds of patterns listed in it (one per line). This is useful when looking for large sets of common typos, autodetection of swear words and known spam on wikis, and finding code snippets that have to be modified for compatibility purposes.		'''grep -f No-No-list *''' to get patterns from to match from the file 'No-No-list' instead of the command line. There can be hundreds of patterns listed in it (one per line). This is useful when looking for large sets of common typos, autodetection of swear words and known spam on wikis, and finding code snippets that have to be modified for compatibility purposes.

@@ Line 30: / Line 30: @@
 Looks like only [[root]] does.
 See also: [[strings]]
 [[Category:FreeBSD Terminology]] [[Category:System Commands]]

← Older revision		Revision as of 00:51, 23 December 2004
Line 31:		Line 31:
	Looks like only [[root]] does.		Looks like only [[root]] does.

		+	See also: [[strings]]

	[[Category:FreeBSD Terminology]] [[Category:System Commands]]		[[Category:FreeBSD Terminology]] [[Category:System Commands]]

← Older revision		Revision as of 20:18, 25 August 2004
Line 1:		Line 1:
−	~~This page should have a description of what~~ grep ~~does~~, and ~~some of~~ the more ~~common ways to use it~~, such as ~~piping the results of~~ [[ls]] or [[cat]] ~~through it~~.	+	[[grep]] returns results that match a string. You can use it to find a line in a file in a directory, by having grep run through the directory and show you what matches your query. Grep accepts input from the commandline, but is more often fed input in conjunction with other commands, such as [[find]], [[ls]] or [[cat]]:
		+
		+	samizdata# ls -la /etc \| grep .conf
		+	-rw-r--r-- 1 root wheel 1163 Jun 5 2003 apmd.conf
		+	-rw-r--r-- 1 root wheel 271 Jun 5 2003 auth.conf
		+	-rw-r--r-- 1 root wheel 2965 Jun 5 2003 devd.conf
		+	-rw-r--r-- 1 root wheel 2073 Jun 5 2003 devfs.conf
		+	-rw-r--r-- 1 root wheel 267 Jun 5 2003 dhclient.conf
		+	-rw-r--r-- 1 root wheel 5159 Jun 5 2003 inetd.conf
		+	-rw-r--r-- 1 root wheel 6521 Jun 5 2003 login.conf
		+	-rw-r--r-- 1 root wheel 65536 Jun 5 2003 login.conf.db
		+	-rw-r--r-- 1 root wheel 503 Jun 5 2003 mac.conf
		+	-rw-r--r-- 1 root wheel 201 Jun 5 2003 make.conf
		+	-rw-r--r-- 1 root wheel 963 Jun 5 2003 manpath.config
		+	-rw-r--r-- 1 root wheel 963 Jun 5 2003 manpath.config.bak
		+	-rw-r--r-- 1 root wheel 783 Jun 5 2003 netconfig
		+	-rw-r--r-- 1 root wheel 1871 Jun 5 2003 newsyslog.conf
		+	-rw------- 1 root wheel 1701 Jun 5 2003 nsmb.conf
		+	-rw-r--r-- 1 root wheel 630 Aug 23 21:46 rc.conf
		+	-rw-r--r-- 1 root wheel 45 Jun 5 2003 resolv.conf
		+	-rw-r--r-- 1 root wheel 367 Jun 5 2003 sysctl.conf
		+	-rw-r--r-- 1 root wheel 1329 Jun 5 2003 syslog.conf
		+	-rw-r--r-- 1 root wheel 2023 Jun 5 2003 usbd.conf
		+
		+	Let's say you want to know which of your users has [[csh]] as their shell:
		+
		+	samizdata# cat passwd \| grep csh
		+	root:*:0:0:Avatar:/root:/bin/csh
		+	samizdata#
		+
		+	Looks like only [[root]] does.
		+

	[[Category:FreeBSD Terminology]] [[Category:System Commands]]		[[Category:FreeBSD Terminology]] [[Category:System Commands]]