Loading... <p style="text-align:left;line-height:21px;background:white">GREP命令,全称:Global search REgular expression and Print out the line.</p> <p style="text-align:left;line-height:21px;background:white">是一个非常强大的文本搜索命令,与SED(stream editor,文本编辑工具)和AWK(文本分析、报告生成器)并称文本处理三剑客。</p> <p style="text-align:left;line-height:21px;background:white"><strong>一.GREP命令基本使用格式</strong></p> <p style="text-align:left;line-height:21px;background:white">grep [OPTIONS] PATTERN [FILE…]</p> <p style="text-align:left;line-height:21px;background:white"> 选项: </p> <p style="text-align:left;line-height:21px;background:white"> –color=auto: 对匹配到的文本着色显示;</p> <p style="text-align:left;line-height:21px;background:white"> -v: 显示不能够被pattern匹配到的行,反转;</p> <p style="text-align:left;line-height:21px;background:white"> -i: 忽略字符大小写;</p> <p style="text-align:left;line-height:21px;background:white"> -o: 仅显示匹配到的字符串;</p> <p style="text-align:left;line-height:21px;background:white"> -q: 静默模式,不输出任何信息;</p> <p style="text-align:left;line-height:21px;background:white"> -A #:after, 后#行</p> <p style="text-align:left;line-height:21px;background:white"> -B #: before, 前#行</p> <p style="text-align:left;line-height:21px;background:white"> -C #:context, 前后各#行</p> <p style="text-align:left;line-height:21px;background:white"> -E:使用ERE; </p> <p style="text-align:left;line-height:21px;background:white"></p> <p style="text-align:left;line-height:21px;background:white">1. –color=auto参数是对匹配到的文本着色显示,Centos7中,grep的命令别名默认带了这个参数。</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# alias grep alias grep='grep --color=auto'</pre> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">2.使用–v 参数显示不能够被匹配到的行</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black"></span></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -v /sbin/nologin /etc/passwd root:x:0:0:root:/root:/bin/bash sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt</pre> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">3.使用–i参数忽略大小写查找</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black"></span></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -i root /etc/fstab /dev/mapper/centos-root / xfs defaults 0 0</pre> <p style="text-align:left;line-height:21px;background:white">4. <span style="font-family:宋体">使用</span>–o参数仅显示匹配到的字符串</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -o root /etc/fstab root</pre> <p style="text-align:left;line-height:21px;background:white">5. <span style="font-family:宋体">使用</span>-A,-B,-C显示之前、之后、(之前之后)的几行</p> <p style="text-align:left;line-height:21px;background:white">-A,显示匹配行之后的几行</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -A2 mail /etc/passwd mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin</pre> <p style="text-align:left;line-height:21px;background:white">-B:显示匹配行之前的几行</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -B2 mail /etc/passwd shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin</pre> <p style="text-align:left;line-height:21px;background:white">-C:显示之前之后的几行</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -C2 mail /etc/passwd shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt mail:x:8:12:mail:/var/spool/mail:/sbin/nologin operator:x:11:0:operator:/root:/sbin/nologin games:x:12:100:games:/usr/games:/sbin/nologin</pre> <p style="text-align:left;line-height:21px;background:white">6.使用-n参数在输出时,显示行号</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -nA2 mail /etc/passwd 9:mail:x:8:12:mail:/var/spool/mail:/sbin/nologin 10-operator:x:11:0:operator:/root:/sbin/nologin 11-games:x:12:100:games:/usr/games:/sbin/nologin</pre> <p style="text-align:left;line-height:21px;background:white">7.用-c参数统计显示匹配的行数</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -c root /etc/passwd 2</pre> <p style="text-align:left;line-height:21px;background:white">8.使用-r进行递归搜索,可以在当前目录及其子目录中进行搜索。</p> <p style="text-align:left;line-height:21px;background:white"></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# grep -r /bashrc /etc/ /etc/bashrc:# /etc/bashrc /etc/profile:# Functions and aliases go in /etc/bashrc /etc/profile.d/256term.sh:# This must be set before reading global initialization such as /etc/bashrc. /etc/skel/.bashrc:if [ -f /etc/bashrc ]; then /etc/skel/.bashrc: . /etc/bashrc</pre> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="color: black">二.GREP的进阶用法</span></strong></span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">GREP命令可以根据用户指定的“模式”对目标文本逐行进行匹配检查,并且打印输出匹配到行(模式,是指由正则表达式字符及文本字符所编写的过滤条件)。</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">REGEXP(正则表达式):由一类特殊字符及文本字符所编写的模式,其中有些字符不表示字符字面意义,而表示控制或通配的功能; </span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">正则表达式分为基本正则表达式(BRE)和 扩展正则表达式(ERE)</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong>2.1</strong><strong>基本正则表达式用法及相关参数:</strong></span></p> <table cellpadding="0" cellspacing="0"> <tbody> <tr class="firstRow"> <td style="border: 1px solid windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="font-family: 华文中宋;color: black">基本正则表达式元字符(BRE):</span></strong></span></p> </td> <td style="border-width: 1px 1px 1px medium;border-style: solid solid solid none;border-color: windowtext windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="font-family: 华文中宋;color: black">参数</span></strong></span></p> </td> </tr> <tr> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">字符匹配:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="font-family: 华文中宋;color: black">.</span></strong><span style="font-family: 华文中宋;color: black">: 匹配任意单个字符;</span></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">[]: 匹配指定范围内的任意单个字符</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> [^]:匹配指定范围外的任意单个字符</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> [:digit:]、[:lower:]、[:upper:]、[:alpha:]、[:alnum:]、[:punct:]、[:space:]</span></p> </td> </tr> <tr> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">匹配次数</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">用在要指定次数的字符后面,用于指定前面的字符要出现的次数;</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">*:匹配前面的字符任意次(有可能是0次);</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 例如: grep "x*y" </span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> abxy</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> xay</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> xxxxxxy</span></p> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><span style="font-family: 华文中宋;color: black"> </span><strong><span style="font-family: 华文中宋;color: red">贪婪模式:转义字符必须加单引号,否则不生效 </span></strong></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> <strong>.*</strong>:任意长度的任意字符;# grep .*y 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\?:匹配其前面的字符0或1次;即前面的可有可无;# grep 'x\?y' 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\+:匹配其前面的字符至少1次;# grep 'x\+y' 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\{m\}:匹配前面的字符m次;# grep 'x\{2\}y' 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\{m,n\}:匹配前面的字符至少m次,至多n次;# grep 'x\{2,4\}y' 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\{0,n\}:匹配前面的字符至多n次;# grep 'x\{0,2\}y' 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">\{m,\}:匹配前面的字符至少m次;# grep 'x\{1,\}y' 1.log</span></p> </td> </tr> <tr> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 位置锚定</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> ^:行首锚定;用于模式的最左侧;# cat /etc/passwd |grep ^root</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> $:行尾锚定;用于模式的最右侧;# cat /etc/passwd |grep /bin/bash$</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> ^PATTERN$: 用于模式匹配整行;# grep ^xxy$ 1.log</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> ^$: 空行;grep ^$ 1.log</span></p> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><span style="font-family: 华文中宋;color: black"> ^[[:space:]]*$: </span> <span style="font-family: 华文中宋;color: black"># grep ^[[:space:]]*$ 1.log</span></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \< 或 \b:词首锚定;用于单词模式的左侧;cat /etc/passwd |grep '\<r'</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \> 或 \b:词尾锚定;用于单词模式的右侧;cat /etc/passwd |grep '\>r'</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \<PATTERN\>:匹配整个单词;cat /etc/passwd |grep '\<root\>'</span></p> </td> </tr> <tr> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 分组:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \(\):将一个或多个字符捆绑在一起,当作一个整体进行处理;# grep '\(xy\)' 1.log</span></p> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><span style="font-family: 华文中宋;color: black"> \(xy\)*ab :</span> <span style="font-family: 华文中宋;color: black"># grep '\(xx\)*y' 1.log</span></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> Note: 分组括号中的模式匹配到的内容会被正则表达式引擎记录于内部的变量中,这些变量的命名方式为: \1, \2, \3, …</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \1: 从左侧起,第一个左括号以及与之匹配右括号之间的模式所匹配到的字符;</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \(ab\+\(xy\)*\):</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \1: ab\+\(xy\)*</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> \2: xy</span></p> </td> </tr> <tr> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" valign="top" width="217"> <p style="line-height:21px"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">后向引用:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" valign="top" width="671"> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 引用前面的分组括号中的模式所匹配字符,(而非模式本身)</span></p> </td> </tr> </tbody> </table> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> <strong>基本练习:</strong></span></p> <p style="text-align:left;line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong>1.</strong><strong>搜索和寻找文件</strong></span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">查找一个文件或者某些包含特定关键字的文件。</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">比如,在Centos7中,默认没有安装ifconfig命令,那么在挂载好CDROM后,需要找出ifconfig命令的包装包(ifconfig 包含在net-tools安装包中),再利用rpm –ivh进行安装:</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <pre class="brush:bash;toolbar:false">[root@192 Packages]# ll |grep –i net-tools -r--r--r--. 2 root root 311020 7月 4 2014 net-tools-2.0-0.17.20131004git.el7.x86_64.rpm</pre> <p style="text-align:left;line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei">2.搜索并过滤文件</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">在示例文件1.log中,有大量的空行,把文件内所有的空行删除并另存为2.log文件。</span></p> <pre class="brush:bash;toolbar:false">[root@192 scripts]# grep -v ^[[:space:]]*$ 1.log >2.log</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">3<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>显示/proc/meminfo文件中以大小s开头的行;(要求:使用两种方式)</span></p> <p class="MsoListParagraph" style="margin-left:60px;text-indent:0;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <pre class="brush:bash;toolbar:false"># grep -i ^s /proc/meminfo # grep ^[Ss] /proc/meminfo</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">4<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>显示/etc/passwd文件中不以/bin/bash结尾的行;</span></p> <pre class="brush:bash;toolbar:false">#grep -v /bin/bash$ /etc/passwd</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">5<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>显示/etc/passwd文件中ID号最大的用户的用户名;</span></p> <pre class="brush:bash;toolbar:false"># sort -t: -k3 -n /etc/passwd |tail -1|cut -f1 -d:</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">6<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>如果用户root存在,显示其默认的shell程序;</span></p> <pre class="brush:bash;toolbar:false"># id root &> /dev/null && grep "^root\>" /etc/passwd | cut -d: -f7</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">7<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>找出/etc/passwd中的两位或三位数;</span></p> <pre class="brush:bash;toolbar:false"> # grep "\<[0-9]\{2,3\}\>" /etc/passwd</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">8<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>显示/etc/rc.d/rc.sysinit文件中,至少以一个空白字符开头的且后面存非空白字符的行;</span></p> <pre class="brush:bash;toolbar:false"># grep "^[[:space:]]\+[^[:space:]]" /etc/grub2.cfg</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">9<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>找出"netstat -tan"命令的结果中以'LISTEN'后跟0、1或多个空白字符结尾的行;</span></p> <pre class="brush:bash;toolbar:false"># netstat -tan | grep "LISTEN[[:space:]]*$"</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">10<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>添加用户bash、testbash、basher以及nologin(其shell为/sbin/nologin);而后找出/etc/passwd文件中用户名同shell名的行;</span></p> <pre class="brush:bash;toolbar:false"># grep "^\([[:alnum:]]\+\>\).*\1$" /etc/passwd</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">11<span style="font-family: 微软雅黑,Microsoft YaHei">.</span>获取当前IP地址,只输出IP地址信息(这道题我做了很多次,一次比一比精简,虽然可能在CentOS6上不通用,但是多思考一下总是对的):</span></p> <p style="margin-left:42px;text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <pre class="brush:bash;toolbar:false">ifconfig |grep ^[[:space:]]*inet |tr -s ' ' |cut -d' ' -f3 |grep ^[1-2]|grep -v 127 ifconfig |grep -A1 eno |grep '^[[:space:]]\+inet' |tr -s ' '|cut -d' ' -f3 ifconfig |grep inet |tr -s ' ' |cut -d' ' -f3 |grep ^[1-2]|grep -v 127 ifconfig |grep -A 1 eno |grep inet |tr -s ' '|cut -f3 -d' ' ifconfig |grep inet.*255$|tr -s ' '|cut -f3 -d' '</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 实例练习:</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 1、写一个脚本,实现如下功能</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 如果user1用户存在,就显示其存在,否则添加之,并显示添加的用户的id号等信息;</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <pre class="brush:bash;toolbar:false"> #!/bin/bash id user1 &> /dev/null && echo "user1 exists." || useradd user1 id user1</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> </span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 2、写一个脚本,完成如下功能</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 如果root用户登录了当前系统,就显示root用户在线;否则说明其未登录;</span></p> <pre class="brush:bash;toolbar:false"># w |grep ^FZ &> /dev/null && echo "Yes" || echo "NO"</pre> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="font-family: 华文中宋;color: black">2.2 egrep</span></strong><strong><span style="font-family: 华文中宋;color: black">及扩展的正则表达式</span></strong></span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> </span><span style="font-family: 微软雅黑,Microsoft YaHei"><span style="font-family: 华文中宋;color: black"> </span>egrep <span style="font-family: 华文中宋;color: black">= grep -E</span></span></p> <p style="line-height:21px;background:white"><span style="font-family: 微软雅黑,Microsoft YaHei"><span style="font-family: 华文中宋;color: black"> </span>egrep<span style="font-family: 华文中宋;color: black"> [OPTIONS] PATTERN [FILE…]</span></span></p> <table cellpadding="0" cellspacing="0"> <tbody> <tr class="firstRow" style="height:6px"> <td style="border: 1px solid windowtext;padding: 0px 7px" height="6" valign="top" width="179"> <p style="line-height:21px"><span style="font-family:华文中宋;color:black">扩展正则表达式的元字符:</span></p> </td> <td style="border-width: 1px 1px 1px medium;border-style: solid solid solid none;border-color: windowtext windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="6" valign="top" width="240"> <p style="line-height:21px"><span style="font-family:华文中宋;color:black">举例</span></p> </td> </tr> <tr style="height:13px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="13" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">字符匹配:</span></p> <p style="line-height:21px"><span style="font-family:华文中宋;color:black"> </span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="13" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">.</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">[]</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">[^]</span></p> </td> </tr> <tr style="height:38px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="38" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">次数匹配:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="38" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">*</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">?:0</span><span style="font-family:华文中宋;color:black">或1次;</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">+</span><span style="font-family:华文中宋;color:black">:1次或多次;</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">{m}</span><span style="font-family:华文中宋;color:black">:匹配m次;</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">{m,n}</span><span style="font-family:华文中宋;color:black">:至少m,至多n次;</span></p> </td> </tr> <tr style="height:25px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="25" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">锚定:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="25" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">^</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">$</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">\<,\b</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">\>,\b</span></p> </td> </tr> <tr style="height:6px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="6" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">分组:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="6" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">()</span></p> </td> </tr> <tr style="height:6px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="6" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">后向引用:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="6" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">\1,\2,…</span></p> </td> </tr> <tr style="height:12px"> <td style="border-width: medium 1px 1px;border-style: none solid solid;border-color: -moz-use-text-color windowtext windowtext;padding: 0px 7px" height="12" valign="top" width="179"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">或者:</span></p> </td> <td style="border-width: medium 1px 1px medium;border-style: none solid solid none;border-color: -moz-use-text-color windowtext windowtext -moz-use-text-color;padding: 0px 7px" height="12" valign="top" width="240"> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">a|b</span></p> <p style="line-height:21px;background:white"><span style="font-family:华文中宋;color:black">C|cat:C</span><span style="font-family:华文中宋;color:black">或cat</span></p> </td> </tr> </tbody> </table> <p></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 基本练习:</span></p> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 1、显示当前系统root、centos或user1用户的默认shell和UID;</span></p> <pre class="brush:bash;toolbar:false"> # grep -E '^(root|centos|user1)\>' /etc/passwd | cut -d: -f1,3,7</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 2、找出/etc/rc.d/init.d/functions文件(centos6)中某单词后面跟一个小括号的行;</span></p> <pre class="brush:bash;toolbar:false"> # grep -E -o "^[_[:alpha:]]+\(\)" /etc/rc.d/init.d/functions</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 3、使用echo输出一绝对路径,使用egrep取出其基名;</span></p> <pre class="brush:bash;toolbar:false"> # echo "/mnt/sdc" | grep -E -o "[^/]+/?$" | cut -d"/" -f1</pre> <p style="line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span><span style="font-family: 微软雅黑,Microsoft YaHei"><strong><span style="font-family: 华文中宋;color: black">2.3 fgrep</span></strong><strong><span style="font-family: 华文中宋;color: black">不支持正则表达式搜索</span></strong></span></p> <p style="text-indent:49px;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei">fgrep只搜索字符串而不是搜索匹配表达式的模式。</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"> 例如,当在用grep –r 搜索/etc及其子目录中所有包括.bash的文件内容时,其中的.则不会被当成正则表达式中所表示的“任意单个字符”</span></p> <p style="text-align:left;line-height:21px;background:white"><span style="color: black;font-family: 微软雅黑,Microsoft YaHei"></span></p> <pre class="brush:bash;toolbar:false">[root@192 ~]# fgrep -r .bashrc /etc/ /etc/profile.d/256term.sh:# Set this variable in your local shell config (such as ~/.bashrc) /etc/bash_completion.d/git:# 2) Add the following line to your .bashrc/.zshrc: /etc/skel/.bash_profile:if [ -f ~/.bashrc ]; then /etc/skel/.bash_profile: . ~/.bashrc /etc/skel/.bashrc:# .bashrc</pre> <p style="text-align:left;line-height:21px;background:white"> </p> <p> </p> 最后修改:2021 年 12 月 10 日 10 : 53 AM © 允许规范转载 赞赏 如果觉得我的文章对你有用,请随意赞赏 赞赏作者 支付宝微信