CVSROOT: /webcvs/grep Module name: grep Changes by: Jim Meyering <meyering> 23/03/22 22:55:22
Index: html_node/Usage.html =================================================================== RCS file: /webcvs/grep/grep/manual/html_node/Usage.html,v retrieving revision 1.33 retrieving revision 1.34 diff -u -b -r1.33 -r1.34 --- html_node/Usage.html 3 Sep 2022 19:33:14 -0000 1.33 +++ html_node/Usage.html 23 Mar 2023 02:55:21 -0000 1.34 @@ -1,11 +1,11 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd";> +<!DOCTYPE html> <html> -<!-- Created by GNU Texinfo 6.8, https://www.gnu.org/software/texinfo/ --> +<!-- Created by GNU Texinfo 7.0dev, https://www.gnu.org/software/texinfo/ --> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <!-- This manual is for grep, a pattern matching engine. -Copyright (C) 1999-2002, 2005, 2008-2022 Free Software Foundation, +Copyright © 1999-2002, 2005, 2008-2023 Free Software Foundation, Inc. Permission is granted to copy, distribute and/or modify this document @@ -14,10 +14,10 @@ Invariant Sections, with no Front-Cover Texts, and with no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License". --> -<title>Usage (GNU Grep 3.8)</title> +<title>Usage (GNU Grep 3.10)</title> -<meta name="description" content="Usage (GNU Grep 3.8)"> -<meta name="keywords" content="Usage (GNU Grep 3.8)"> +<meta name="description" content="Usage (GNU Grep 3.10)"> +<meta name="keywords" content="Usage (GNU Grep 3.10)"> <meta name="resource-type" content="document"> <meta name="distribution" content="global"> <meta name="Generator" content="makeinfo"> @@ -31,21 +31,9 @@ <link href="Regular-Expressions.html" rel="prev" title="Regular Expressions"> <style type="text/css"> <!-- -a.copiable-anchor {visibility: hidden; text-decoration: none; line-height: 0em} -a.summary-letter {text-decoration: none} -blockquote.indentedblock {margin-right: 0em} -div.display {margin-left: 3.2em} +a.copiable-link {visibility: hidden; text-decoration: none; line-height: 0em} div.example {margin-left: 3.2em} -kbd {font-style: oblique} -pre.display {font-family: inherit} -pre.format {font-family: inherit} -pre.menu-comment {font-family: serif} -pre.menu-preformatted {font-family: serif} -span.nolinebreak {white-space: nowrap} -span.roman {font-family: initial; font-weight: normal} -span.sansserif {font-family: sans-serif; font-weight: normal} -span:hover a.copiable-anchor {visibility: visible} -ul.no-bullet {list-style: none} +span:hover a.copiable-link {visibility: visible} --> </style> <link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css";> @@ -54,317 +42,317 @@ </head> <body lang="en"> -<div class="chapter" id="Usage"> -<div class="header"> +<div class="chapter-level-extent" id="Usage"> +<div class="nav-panel"> <p> Next: <a href="Performance.html" accesskey="n" rel="next">Performance</a>, Previous: <a href="Regular-Expressions.html" accesskey="p" rel="prev">Regular Expressions</a>, Up: <a href="index.html" accesskey="u" rel="up">grep</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p> </div> <hr> -<span id="Usage-1"></span><h2 class="chapter">4 Usage</h2> +<h2 class="chapter" id="Usage-1"><span>4 Usage<a class="copiable-link" href="#Usage-1"> ¶</a></span></h2> -<span id="index-usage_002c-examples"></span> -<p>Here is an example command that invokes GNU <code>grep</code>: +<a class="index-entry-id" id="index-usage_002c-examples"></a> +<p>Here is an example command that invokes GNU <code class="command">grep</code>: </p> <div class="example"> -<pre class="example">grep -i 'hello.*world' menu.h main.c +<pre class="example-preformatted">grep -i 'hello.*world' menu.h main.c </pre></div> -<p>This lists all lines in the files <samp>menu.h</samp> and <samp>main.c</samp> that -contain the string ‘<samp>hello</samp>’ followed by the string ‘<samp>world</samp>’; -this is because ‘<samp>.*</samp>’ matches zero or more characters within a line. -See <a href="Regular-Expressions.html">Regular Expressions</a>. -The <samp>-i</samp> option causes <code>grep</code> -to ignore case, causing it to match the line ‘<samp>Hello, world!</samp>’, which +<p>This lists all lines in the files <samp class="file">menu.h</samp> and <samp class="file">main.c</samp> that +contain the string ‘<samp class="samp">hello</samp>’ followed by the string ‘<samp class="samp">world</samp>’; +this is because ‘<samp class="samp">.*</samp>’ matches zero or more characters within a line. +See <a class="xref" href="Regular-Expressions.html">Regular Expressions</a>. +The <samp class="option">-i</samp> option causes <code class="command">grep</code> +to ignore case, causing it to match the line ‘<samp class="samp">Hello, world!</samp>’, which it would not otherwise match. </p> <p>Here is a more complex example, showing the location and contents of any line -containing ‘<samp>f</samp>’ and ending in ‘<samp>.c</samp>’, +containing ‘<samp class="samp">f</samp>’ and ending in ‘<samp class="samp">.c</samp>’, within all files in the current directory whose names -start with non-‘<samp>.</samp>’, contain ‘<samp>g</samp>’, and end in ‘<samp>.h</samp>’. -The <samp>-n</samp> option outputs line numbers, the <samp>--</samp> argument +start with non-‘<samp class="samp">.</samp>’, contain ‘<samp class="samp">g</samp>’, and end in ‘<samp class="samp">.h</samp>’. +The <samp class="option">-n</samp> option outputs line numbers, the <samp class="option">--</samp> argument treats any later arguments as file names not options even if -<code>*g*.h</code> expands to a file name that starts with ‘<samp>-</samp>’, -and the empty file <samp>/dev/null</samp> causes file names to be output -even if only one file name happens to be of the form ‘<samp>*g*.h</samp>’. +<code class="code">*g*.h</code> expands to a file name that starts with ‘<samp class="samp">-</samp>’, +and the empty file <samp class="file">/dev/null</samp> causes file names to be output +even if only one file name happens to be of the form ‘<samp class="samp">*g*.h</samp>’. </p> <div class="example"> -<pre class="example">grep -n -- 'f.*\.c$' *g*.h /dev/null +<pre class="example-preformatted">grep -n -- 'f.*\.c$' *g*.h /dev/null </pre></div> <p>Note that the regular expression syntax used in the pattern differs from the globbing syntax that the shell uses to match file names. </p> -<p>See <a href="Invoking.html">Invoking <code>grep</code></a>, for more details about -how to invoke <code>grep</code>. +<p>See <a class="xref" href="Invoking.html">Invoking <code class="command">grep</code></a>, for more details about +how to invoke <code class="command">grep</code>. </p> -<span id="index-using-grep_002c-Q_0026A"></span> -<span id="index-FAQ-about-grep-usage"></span> -<p>Here are some common questions and answers about <code>grep</code> usage. +<a class="index-entry-id" id="index-using-grep_002c-Q_0026A"></a> +<a class="index-entry-id" id="index-FAQ-about-grep-usage"></a> +<p>Here are some common questions and answers about <code class="command">grep</code> usage. </p> -<ol> +<ol class="enumerate"> <li> How can I list just the names of matching files? <div class="example"> -<pre class="example">grep -l 'main' test-*.c +<pre class="example-preformatted">grep -l 'main' test-*.c </pre></div> -<p>lists names of ‘<samp>test-*.c</samp>’ files in the current directory whose contents -mention ‘<samp>main</samp>’. +<p>lists names of ‘<samp class="samp">test-*.c</samp>’ files in the current directory whose contents +mention ‘<samp class="samp">main</samp>’. </p> </li><li> How do I search directories recursively? <div class="example"> -<pre class="example">grep -r 'hello' /home/gigi +<pre class="example-preformatted">grep -r 'hello' /home/gigi </pre></div> -<p>searches for ‘<samp>hello</samp>’ in all files -under the <samp>/home/gigi</samp> directory. +<p>searches for ‘<samp class="samp">hello</samp>’ in all files +under the <samp class="file">/home/gigi</samp> directory. For more control over which files are searched, -use <code>find</code> and <code>grep</code>. +use <code class="command">find</code> and <code class="command">grep</code>. For example, the following command searches only C files: </p> <div class="example"> -<pre class="example">find /home/gigi -name '*.c' ! -type d \ +<pre class="example-preformatted">find /home/gigi -name '*.c' ! -type d \ -exec grep -H 'hello' '{}' + </pre></div> <p>This differs from the command: </p> <div class="example"> -<pre class="example">grep -H 'hello' /home/gigi/*.c +<pre class="example-preformatted">grep -H 'hello' /home/gigi/*.c </pre></div> -<p>which merely looks for ‘<samp>hello</samp>’ in non-hidden C files in -<samp>/home/gigi</samp> whose names end in ‘<samp>.c</samp>’. -The <code>find</code> command line above is more similar to the command: +<p>which merely looks for ‘<samp class="samp">hello</samp>’ in non-hidden C files in +<samp class="file">/home/gigi</samp> whose names end in ‘<samp class="samp">.c</samp>’. +The <code class="command">find</code> command line above is more similar to the command: </p> <div class="example"> -<pre class="example">grep -r --include='*.c' 'hello' /home/gigi +<pre class="example-preformatted">grep -r --include='*.c' 'hello' /home/gigi </pre></div> -</li><li> What if a pattern or file has a leading ‘<samp>-</samp>’? +</li><li> What if a pattern or file has a leading ‘<samp class="samp">-</samp>’? For example: <div class="example"> -<pre class="example">grep "$pattern" * +<pre class="example-preformatted">grep "$pattern" * </pre></div> -<p>can behave unexpectedly if the value of ‘<samp>pattern</samp>’ begins with ‘<samp>-</samp>’, -or if the ‘<samp>*</samp>’ expands to a file name with leading ‘<samp>-</samp>’. -To avoid the problem, you can use <samp>-e</samp> for patterns and leading -‘<samp>./</samp>’ for files: +<p>can behave unexpectedly if the value of ‘<samp class="samp">pattern</samp>’ begins with ‘<samp class="samp">-</samp>’, +or if the ‘<samp class="samp">*</samp>’ expands to a file name with leading ‘<samp class="samp">-</samp>’. +To avoid the problem, you can use <samp class="option">-e</samp> for patterns and leading +‘<samp class="samp">./</samp>’ for files: </p> <div class="example"> -<pre class="example">grep -e "$pattern" ./* +<pre class="example-preformatted">grep -e "$pattern" ./* </pre></div> <p>searches for all lines matching the pattern in all the working -directory’s files whose names do not begin with ‘<samp>.</samp>’. -Without the <samp>-e</samp>, <code>grep</code> might treat the pattern as an -option if it begins with ‘<samp>-</samp>’. Without the ‘<samp>./</samp>’, there might -be similar problems with file names beginning with ‘<samp>-</samp>’. +directory’s files whose names do not begin with ‘<samp class="samp">.</samp>’. +Without the <samp class="option">-e</samp>, <code class="command">grep</code> might treat the pattern as an +option if it begins with ‘<samp class="samp">-</samp>’. Without the ‘<samp class="samp">./</samp>’, there might +be similar problems with file names beginning with ‘<samp class="samp">-</samp>’. </p> -<p>Alternatively, you can use ‘<samp>--</samp>’ before the pattern and file names: +<p>Alternatively, you can use ‘<samp class="samp">--</samp>’ before the pattern and file names: </p> <div class="example"> -<pre class="example">grep -- "$pattern" * +<pre class="example-preformatted">grep -- "$pattern" * </pre></div> -<p>This also fixes the problem, except that if there is a file named ‘<samp>-</samp>’, -<code>grep</code> misinterprets the ‘<samp>-</samp>’ as standard input. +<p>This also fixes the problem, except that if there is a file named ‘<samp class="samp">-</samp>’, +<code class="command">grep</code> misinterprets the ‘<samp class="samp">-</samp>’ as standard input. </p> </li><li> Suppose I want to search for a whole word, not a part of a word? <div class="example"> -<pre class="example">grep -w 'hello' test*.log +<pre class="example-preformatted">grep -w 'hello' test*.log </pre></div> -<p>searches only for instances of ‘<samp>hello</samp>’ that are entire words; -it does not match ‘<samp>Othello</samp>’. -For more control, use ‘<samp>\<</samp>’ and -‘<samp>\></samp>’ to match the start and end of words. +<p>searches only for instances of ‘<samp class="samp">hello</samp>’ that are entire words; +it does not match ‘<samp class="samp">Othello</samp>’. +For more control, use ‘<samp class="samp">\<</samp>’ and +‘<samp class="samp">\></samp>’ to match the start and end of words. For example: </p> <div class="example"> -<pre class="example">grep 'hello\>' test*.log +<pre class="example-preformatted">grep 'hello\>' test*.log </pre></div> -<p>searches only for words ending in ‘<samp>hello</samp>’, so it matches the word -‘<samp>Othello</samp>’. +<p>searches only for words ending in ‘<samp class="samp">hello</samp>’, so it matches the word +‘<samp class="samp">Othello</samp>’. </p> </li><li> How do I output context around the matching lines? <div class="example"> -<pre class="example">grep -C 2 'hello' test*.log +<pre class="example-preformatted">grep -C 2 'hello' test*.log </pre></div> <p>prints two lines of context around each matching line. </p> -</li><li> How do I force <code>grep</code> to print the name of the file? +</li><li> How do I force <code class="command">grep</code> to print the name of the file? -<p>Append <samp>/dev/null</samp>: +<p>Append <samp class="file">/dev/null</samp>: </p> <div class="example"> -<pre class="example">grep 'eli' /etc/passwd /dev/null +<pre class="example-preformatted">grep 'eli' /etc/passwd /dev/null </pre></div> <p>gets you: </p> <div class="example"> -<pre class="example">/etc/passwd:eli:x:2098:1000:Eli Smith:/home/eli:/bin/bash +<pre class="example-preformatted">/etc/passwd:eli:x:2098:1000:Eli Smith:/home/eli:/bin/bash </pre></div> -<p>Alternatively, use <samp>-H</samp>, which is a GNU extension: +<p>Alternatively, use <samp class="option">-H</samp>, which is a GNU extension: </p> <div class="example"> -<pre class="example">grep -H 'eli' /etc/passwd +<pre class="example-preformatted">grep -H 'eli' /etc/passwd </pre></div> -</li><li> Why do people use strange regular expressions on <code>ps</code> output? +</li><li> Why do people use strange regular expressions on <code class="command">ps</code> output? <div class="example"> -<pre class="example">ps -ef | grep '[c]ron' +<pre class="example-preformatted">ps -ef | grep '[c]ron' </pre></div> <p>If the pattern had been written without the square brackets, it would -have matched not only the <code>ps</code> output line for <code>cron</code>, -but also the <code>ps</code> output line for <code>grep</code>. +have matched not only the <code class="command">ps</code> output line for <code class="command">cron</code>, +but also the <code class="command">ps</code> output line for <code class="command">grep</code>. Note that on some platforms, -<code>ps</code> limits the output to the width of the screen; -<code>grep</code> does not have any limit on the length of a line +<code class="command">ps</code> limits the output to the width of the screen; +<code class="command">grep</code> does not have any limit on the length of a line except the available memory. </p> -</li><li> Why does <code>grep</code> report “Binary file matches”? +</li><li> Why does <code class="command">grep</code> report “Binary file matches”? -<p>If <code>grep</code> listed all matching “lines” from a binary file, it +<p>If <code class="command">grep</code> listed all matching “lines” from a binary file, it would probably generate output that is not useful, and it might even muck up your display. -So GNU <code>grep</code> suppresses output from +So GNU <code class="command">grep</code> suppresses output from files that appear to be binary files. -To force GNU <code>grep</code> +To force GNU <code class="command">grep</code> to output lines even from files that appear to be binary, use the -<samp>-a</samp> or ‘<samp>--binary-files=text</samp>’ option. +<samp class="option">-a</samp> or ‘<samp class="samp">--binary-files=text</samp>’ option. To eliminate the -“Binary file matches” messages, use the <samp>-I</samp> or -‘<samp>--binary-files=without-match</samp>’ option. +“Binary file matches” messages, use the <samp class="option">-I</samp> or +‘<samp class="samp">--binary-files=without-match</samp>’ option. </p> -</li><li> Why doesn’t ‘<samp>grep -lv</samp>’ print non-matching file names? +</li><li> Why doesn’t ‘<samp class="samp">grep -lv</samp>’ print non-matching file names? -<p>‘<samp>grep -lv</samp>’ lists the names of all files containing one or more +<p>‘<samp class="samp">grep -lv</samp>’ lists the names of all files containing one or more lines that do not match. To list the names of all files that contain no -matching lines, use the <samp>-L</samp> or <samp>--files-without-match</samp> +matching lines, use the <samp class="option">-L</samp> or <samp class="option">--files-without-match</samp> option. </p> -</li><li> I can do “OR” with ‘<samp>|</samp>’, but what about “AND”? +</li><li> I can do “OR” with ‘<samp class="samp">|</samp>’, but what about “AND”? <div class="example"> -<pre class="example">grep 'paul' /etc/motd | grep 'franc,ois' +<pre class="example-preformatted">grep 'paul' /etc/motd | grep 'franc,ois' </pre></div> -<p>finds all lines that contain both ‘<samp>paul</samp>’ and ‘<samp>franc,ois</samp>’. +<p>finds all lines that contain both ‘<samp class="samp">paul</samp>’ and ‘<samp class="samp">franc,ois</samp>’. </p> </li><li> Why does the empty pattern match every input line? -<p>The <code>grep</code> command searches for lines that contain strings +<p>The <code class="command">grep</code> command searches for lines that contain strings that match a pattern. Every line contains the empty string, so an -empty pattern causes <code>grep</code> to find a match on each line. It -is not the only such pattern: ‘<samp>^</samp>’, ‘<samp>$</samp>’, and many -other patterns cause <code>grep</code> to match every line. -</p> -<p>To match empty lines, use the pattern ‘<samp>^$</samp>’. To match blank -lines, use the pattern ‘<samp>^[[:blank:]]*$</samp>’. To match no lines at -all, use an extended regular expression like ‘<samp>a^</samp>’ or ‘<samp>$a</samp>’. +empty pattern causes <code class="command">grep</code> to find a match on each line. It +is not the only such pattern: ‘<samp class="samp">^</samp>’, ‘<samp class="samp">$</samp>’, and many +other patterns cause <code class="command">grep</code> to match every line. +</p> +<p>To match empty lines, use the pattern ‘<samp class="samp">^$</samp>’. To match blank +lines, use the pattern ‘<samp class="samp">^[[:blank:]]*$</samp>’. To match no lines at +all, use an extended regular expression like ‘<samp class="samp">a^</samp>’ or ‘<samp class="samp">$a</samp>’. To match every line, a portable script should use a pattern like -‘<samp>^</samp>’ instead of the empty pattern, as POSIX does not specify the +‘<samp class="samp">^</samp>’ instead of the empty pattern, as POSIX does not specify the behavior of the empty pattern. </p> </li><li> How can I search in both standard input and in files? -<p>Use the special file name ‘<samp>-</samp>’: +<p>Use the special file name ‘<samp class="samp">-</samp>’: </p> <div class="example"> -<pre class="example">cat /etc/passwd | grep 'alain' - /etc/motd +<pre class="example-preformatted">cat /etc/passwd | grep 'alain' - /etc/motd </pre></div> -</li><li> Why can’t I combine the shell’s ‘<samp>set -e</samp>’ with <code>grep</code>? +</li><li> Why can’t I combine the shell’s ‘<samp class="samp">set -e</samp>’ with <code class="command">grep</code>? -<p>The <code>grep</code> command follows the convention of programs like -<code>cmp</code> and <code>diff</code> where an exit status of 1 is not an -error. The shell command ‘<samp>set -e</samp>’ causes the shell to exit if +<p>The <code class="command">grep</code> command follows the convention of programs like +<code class="command">cmp</code> and <code class="command">diff</code> where an exit status of 1 is not an +error. The shell command ‘<samp class="samp">set -e</samp>’ causes the shell to exit if any subcommand exits with nonzero status, and this will cause the -shell to exit merely because <code>grep</code> selected no lines, +shell to exit merely because <code class="command">grep</code> selected no lines, which is ordinarily not what you want. </p> -<p>There is a related problem with Bash’s <code>set -e -o pipefail</code>. -Since <code>grep</code> does not always read all its input, a command -outputting to a pipe read by <code>grep</code> can fail when -<code>grep</code> exits before reading all its input, and the command’s +<p>There is a related problem with Bash’s <code class="command">set -e -o pipefail</code>. +Since <code class="command">grep</code> does not always read all its input, a command +outputting to a pipe read by <code class="command">grep</code> can fail when +<code class="command">grep</code> exits before reading all its input, and the command’s failure can cause Bash to exit. </p> </li><li> Why is this back-reference failing? <div class="example"> -<pre class="example">echo 'ba' | grep -E '(a)\1|b\1' +<pre class="example-preformatted">echo 'ba' | grep -E '(a)\1|b\1' </pre></div> -<p>This outputs an error message, because the second ‘<samp>\1</samp>’ +<p>This outputs an error message, because the second ‘<samp class="samp">\1</samp>’ has nothing to refer back to, meaning it will never match anything. </p> </li><li> How can I match across lines? <p>Standard grep cannot do this, as it is fundamentally line-based. -Therefore, merely using the <code>[:space:]</code> character class does not +Therefore, merely using the <code class="code">[:space:]</code> character class does not match newlines in the way you might expect. </p> -<p>With the GNU <code>grep</code> option <samp>-z</samp> (<samp>--null-data</samp>), each -input and output “line” is null-terminated; see <a href="Other-Options.html">Other Options</a>. Thus, +<p>With the GNU <code class="command">grep</code> option <samp class="option">-z</samp> (<samp class="option">--null-data</samp>), each +input and output “line” is null-terminated; see <a class="pxref" href="Other-Options.html">Other Options</a>. Thus, you can match newlines in the input, but typically if there is a match the entire input is output, so this usage is often combined with -output-suppressing options like <samp>-q</samp>, e.g.: +output-suppressing options like <samp class="option">-q</samp>, e.g.: </p> <div class="example"> -<pre class="example">printf 'foo\nbar\n' | grep -z -q 'foo[[:space:]]\+bar' +<pre class="example-preformatted">printf 'foo\nbar\n' | grep -z -q 'foo[[:space:]]\+bar' </pre></div> <p>If this does not suffice, you can transform the input -before giving it to <code>grep</code>, or turn to <code>awk</code>, -<code>sed</code>, <code>perl</code>, or many other utilities that are +before giving it to <code class="command">grep</code>, or turn to <code class="command">awk</code>, +<code class="command">sed</code>, <code class="command">perl</code>, or many other utilities that are designed to operate across lines. </p> -</li><li> What do <code>grep</code>, <samp>-E</samp>, and <samp>-F</samp> stand for? +</li><li> What do <code class="command">grep</code>, <samp class="option">-E</samp>, and <samp class="option">-F</samp> stand for? -<p>The name <code>grep</code> comes from the way line editing was done on Unix. +<p>The name <code class="command">grep</code> comes from the way line editing was done on Unix. For example, -<code>ed</code> uses the following syntax +<code class="command">ed</code> uses the following syntax to print a list of matching lines on the screen: </p> <div class="example"> -<pre class="example">global/regular expression/print +<pre class="example-preformatted">global/regular expression/print g/re/p </pre></div> -<p>The <samp>-E</samp> option stands for Extended <code>grep</code>. -The <samp>-F</samp> option stands for Fixed <code>grep</code>; +<p>The <samp class="option">-E</samp> option stands for Extended <code class="command">grep</code>. +The <samp class="option">-F</samp> option stands for Fixed <code class="command">grep</code>; </p> -</li><li> What happened to <code>egrep</code> and <code>fgrep</code>? +</li><li> What happened to <code class="command">egrep</code> and <code class="command">fgrep</code>? -<p>7th Edition Unix had commands <code>egrep</code> and <code>fgrep</code> -that were the counterparts of the modern ‘<samp>grep -E</samp>’ and ‘<samp>grep -F</samp>’. -Although breaking up <code>grep</code> into three programs was perhaps -useful on the small computers of the 1970s, <code>egrep</code> and -<code>fgrep</code> were not standardized by POSIX and are no longer needed. -In the current GNU implementation, <code>egrep</code> and <code>fgrep</code> -issue a warning and then act like their modern counterparts; +<p>7th Edition Unix had commands <code class="command">egrep</code> and <code class="command">fgrep</code> +that were the counterparts of the modern ‘<samp class="samp">grep -E</samp>’ and ‘<samp class="samp">grep -F</samp>’. +Although breaking up <code class="command">grep</code> into three programs was perhaps +useful on the small computers of the 1970s, <code class="command">egrep</code> and +<code class="command">fgrep</code> were deemed obsolescent by POSIX in 1992, +removed from POSIX in 2001, deprecated by GNU Grep 2.5.3 in 2007, +and changed to issue obsolescence warnings by GNU Grep 3.8 in 2022; eventually, they are planned to be removed entirely. </p> <p>If you prefer the old names, you can use use your own substitutes, -such as a shell script named <code>egrep</code> with the following +such as a shell script named <code class="command">egrep</code> with the following contents: </p> <div class="example"> -<pre class="example">#!/bin/sh +<pre class="example-preformatted">#!/bin/sh exec grep -E "$@" </pre></div> @@ -373,7 +361,7 @@ </div> <hr> -<div class="header"> +<div class="nav-panel"> <p> Next: <a href="Performance.html">Performance</a>, Previous: <a href="Regular-Expressions.html">Regular Expressions</a>, Up: <a href="index.html">grep</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Index.html" title="Index" rel="index">Index</a>]</p> </div>
