Shell编程之正则表达式（二）
2019-10-12 00:19
1156 查看
文本处理器
在
Linux/UNIX系统中包含很多种文本处理器或文本编辑器,其中包括我们之前学习过的
VIM编辑器与
grep等。而
grep、sed、awk更是
shell编程中经常用到的文本处理工具，被称之为
Shell编程三剑客。
sed 工具
sed（Stream EDitor）是一个强大而简单的文本解析转换工具，可以读取文本，并根据指定的条件对文本内容进行编辑（删除、替换、添加、移动等），最后输出所有行或者仅输出处理的某些行。
sed也可以在无交互的情况下实现相复杂的文本处理操作，被广泛应用于
Shell脚本中，用以完成各种自动化处理任务。
-
sed
的工作流程主要包括读取、执行和显示三个过程 读取：sed
从输入流（文件、管道、标准输入）中读取一行内容并存储到临时的缓 冲区中（又称模式空间，pattern space
） - 执行：默认情况下，所有的
sed
命令都在模式空间中顺序地执行，除非指定了行的地址，否则sed
命令将会在所有的行上依次执行 - 显示：发送修改后的内容到输出流。再发送数据后，模式空间将会被清空
- 在所有的文件内容都被处理完成之前，上述过程将重复执行，直至所有内容被处理完
sed 命令常见用法
-
sed 命令有两种格式：
sed [选项] '操作' 参数 //“参数”是指操作的目标文件，当存在多个操作对象时用，文件之间用逗号“，”分隔 或 sed [选项] -f scriptfile 参数 // scriptfile 表示脚本文件，需要用“-f”选项指定
-
常见sed命令选项
-e
或--expression=
：表示用指定命令或者脚本来处理输入的文本文件 -f
或--file=
：表示用指定的脚本文件来处理输入的文本文件-h
或--help
：显示帮助-n
、--quiet
或silent
：表示仅显示处理后的结果-i
：直接编辑文本文件
a：增加，在当前行下面增加一行指定内容
c：替换，将选定行替换为指定内容
d：删除，删除选定的行
i：插入，在选定行上面插入一行指定内容
p：打印，如果同时指定行，表示打印指定行；如果不指定行，则表示打印所有内容；如果有非打印字符，则以
ASCII码输出。其通常与
“-n”选项一起使用
s：替换，替换指定字符
y：字符转换
示例
1）输出符合条件的文本（p 表示正常输出）
[root@localhost opt]# sed -n 'p' httpd.txt //输出文件所有内容，等同 cat httpd.txt # # This is the main Apache HTTP server configuration file. It contains the # configuration directives that give the server its instructions. # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # In particular, see # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> # for a discussion of each configuration directive. # # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so 'log/access_log' # with ServerRoot set to '/www' will be interpreted by the # server as '/www/log/access_log', where as '/log/access_log' will be ...//省略部分内容....
[root@localhost opt]# sed -n '3p' httpd.txt //输出第3行内容 # configuration directives that give the server its instructions.
[root@localhost opt]# sed -n '3,5p' httpd.txt //输出3~5行内容 # configuration directives that give the server its instructions. # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # In particular, see
[root@localhost opt]# sed -n 'p;n' httpd.txt //输出所有奇数行内容，n表示读入下一行资料 # # configuration directives that give the server its instructions. # In particular, see # for a discussion of each configuration directive. # Do NOT simply read the instructions in here without understanding # consult the online docs. You have been warned. # Configuration and logfile names: If the filenames you specify for many # server will use that explicit path. If the filenames do *not* begin # with ServerRoot set to '/www' will be interpreted by the # interpreted as '/log/access_log'. ...//省略部分内容....
[root@localhost opt]# sed -n 'n;p' httpd.txt //输出所有偶数行 # This is the main Apache HTTP server configuration file. It contains the # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> # # what they do. They're here only as hints or reminders. If you are unsure # # of the server's control files begin with "/" (or "drive:/" for Win32), the ...//省略部分内容....
[root@localhost opt]# sed -n '1,5{p;n}' httpd.txt //输出1~5行之间的奇数行（1、3、5行）
#
# configuration directives that give the server its instructions.
# In particular, see
[root@localhost opt]# sed -n '350,${n;p}' httpd.txt //输出第350行至文件尾之间的偶数行
#
IncludeOptional conf.d/*.conf
short
wod
woooood
AxyzxyzC
//在执行此命令时，读取的第1行时第350行，读取的第二行是第351行，依次类推，所以输出的偶数行是文件的第351行、第353行直至文件结尾，其中包括空行
sed
命令结合正则表达式时，格式略有不同，正则表达式以“/”
包围
[root@localhost opt]# sed -n '/the/p' httpd.txt //输出包含the的行 # This is the main Apache HTTP server configuration file. It conta 16d0 ins the # configuration directives that give the server its instructions. # Do NOT simply read the instructions in here without understanding # what they do. They're here only as hints or reminders. If you are unsure # consult the online docs. You have been warned. # Configuration and logfile names: If the filenames you specify for many # of the server's control files begin with "/" (or "drive:/" for Win32), the # server will use that explicit path. If the filenames do *not* begin # with "/", the value of ServerRoot is prepended -- so 'log/access_log' # with ServerRoot set to '/www' will be interpreted by the
[root@localhost opt]# sed -n '4,/the/p' httpd.txt //输出从第4行至第一个包含the的行 # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # In particular, see # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> # for a discussion of each configuration directive. # # Do NOT simply read the instructions in here without understanding
[root@localhost opt]# sed -n '/the/=' httpd.txt //输出包含the的所在行的行号，等号（=）用来输出行号 2 3 9 10 11 13 14 ...//省略部分内容...
[root@localhost opt]# sed -n '/^sh/p' httpd.txt //输出以sh开头的行 shirt short
[root@localhost opt]# sed -n '/[0-9]$/p' httpd.txt //输出以数字结尾的行 #Listen 12.34.56.78:80 Listen 80 #ServerName www.example.com:80 AddDefaultCharset UTF-8
[root@localhost opt]# sed -n '/\<wood\>/p' httpd.txt //输出包含的单词wood的行，\<\>代表单词边界 wood
2）删除符合条件的文本（d）
- 下面命令中
nl
命令用于计算文件的行数，结合该命令可以更加直观地查看到命令执行的结果。
[root@localhost opt]# nl httpd.txt | sed '3d' //删除第3行 1 u 2 # This is the main Apache HTTP server configuration file. It contains the 4 # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. 5 # In particular, see 6 # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> 7 # for a discussion of each configuration directive. ...//省略部分内容...
[root@localhost opt]# nl httpd.txt | sed '3,5d' //删除3~5行 1 u 2 # This is the main Apache HTTP server configuration file. It contains the 6 # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> 7 # for a discussion of each configuration directive. ...//省略部分内容...
[root@localhost opt]# nl httpd.txt | sed '/wood/d' //删除包含wood的行，原第321行被删除 1 u //删除不包含cross 的行,用!符号表示取反操作,如'/cross/！d' 2 # This is the main Apache HTTP server configuration file. It contains the 3 # configuration directives that give the server its instructions. ...//省略部分内容... 318 short 319 wd 320 wod 322 woooood 323 AxyzC 324 AxyzxyzC
[root@localhost opt]# sed '/^[a-z]/d' httpd.txt //删除以小写字母开头的行 # This is the main Apache HTTP server configuration file. It contains the # configuration directives that give the server its instructions. ...//省略部分内容... # Load config files in the "/etc/httpd/conf.d" directory, if any. IncludeOptional conf.d/*.conf AxyzC AxyzxyzC
[root@localhost opt]# sed '/\.$/d' httpd.txt //删除以“.”结尾的行 u # This is the main Apache HTTP server configuration file. It contains the # In particular, see # <URL:http://httpd.apache.org/docs/2.4/mod/directives.html> ...//省略部分内容...
[root@localhost opt]# sed '/^$/d' httpd.txt //删除所有空行
u
# This is the main Apache HTTP server configuration file. It contains the
# configuration directives that give the server its instructions.
# See <URL:http://httpd.apache.org/docs/2.4/> for detailed information.
# In particular, see
# <URL:http://httpd.apache.org/docs/2.4/mod/directives.html>
# for a discussion of each configuration directive.
//注意： 若是删除重复的空行，即连续的空行只保留一个， 执行“ sed –e ‘/^$/{n;/^$/d}’ httpd.txt”命令即可实现。其效果与“cat -s test.txt”相同，n 表示读下一行数据。
3）替换符合条件的文本
- 在使用
sed
命令进行替换操作时需要用到s
（字符串替换）、c
（整行/整块替换）、y
（字符转换）命令选项
[root@localhost opt]# sed 's/the/THE/' httpd.txt //将每行中第一个the替换为THE u # This is THE main Apache HTTP server configuration file. It contains the # configuration directives that give THE server its instructions. # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # In particular, see ...//省略部分内容...
[root@localhost opt]# vim aaa.txt //编辑一个新文件 llllll llllll llllll //编辑内容 llllll llllll llllll ~ ~ :wq //保存退出 [root@localhost opt]# sed 's/l/L/3' aaa.txt //将每行中第3个l替换为L llLlll llLlll //显示替换后内容 llLlll llLlll 5ac llLlll llLlll
[root@localhost opt]# sed 's/the/THE/g' httpd.txt //将文件中多有的the替换为THE u # This is THE main Apache HTTP server configuration file. It contains THE # configuration directives that give THE server its instructions. # See <URL:http://httpd.apache.org/docs/2.4/> for detailed information. # In particular, see ...//省略部分内容...
[root@localhost opt]# sed 's/o//g' httpd.txt //将文件中所有的o删除（替换为空串） u # This is the main Apache HTTP server cnfiguratin file. It cntains the # cnfiguratin directives that give the server its instructins. ...//省略部分内容... shirt shrt wd wd wd wd AxyzC AxyzxyzC
[root@localhost opt]# sed 's/^/#/' aaa.txt //在每行行首插入#号 #llllll #llllll #llllll #llllll #llllll #llllll
[root@localhost opt]# sed 's/$/eof/' aaa.txt //在每行行尾插入字符串eof lllllleof lllllleof lllllleof lllllleof lllllleof lllllleof
[root@localhost opt]# vim aaa.txt //编辑文件 llllll llllll llllll llllll llllll llllll aaaaaa aaaaaa //添加内容 aaaaaa aaaaaa aaaaaa ~ ~ :wq //保存退出 [root@lo b26 calhost opt]# sed '/a/s/^/#/' aaa.txt //在包含 a 的每行行首插入#号 llllll llllll llllll llllll llllll llllll #aaaaaa #aaaaaa #aaaaaa #aaaaaa #aaaaaa
[root@localhost opt]# sed '3,5s/l/L/g' aaa.txt //将第 3~5 行中的所有 l 替换为 L llllll llllll LLLLLL LLLLLL LLLLLL llllll aaaaaa aaaaaa aaaaaa aaaaaa aaaaaa
[root@localhost opt]# vim bbb.txt //编辑一个新文件 this is the wood wood wod //编辑内容 the wood this is test ~ ~ :wq //保存退出 [root@localhost opt]# sed '/the/s/o/O/g' bbb.txt //将包含 the 的所有行中的 o 都替换为 O this is the wOOd wood wod the wOOd this is test
4） 迁移符合条件的文本
H
，复制到剪贴板；g
、G
，将剪贴板中的数据覆盖/追加至指定行；w
，保存为文件；r
，读取指定文件；a
，追加指定内容。
[root@localhost opt]# sed '/the/{H;d};$G' bbb.txt //将包含the 的行迁移至文件末尾,{;}用于多个操作
this is
wood
wod
this is test
the wood
the wood
[root@localhost opt]# sed '1,3{H;d};8G' aaa.txt //将1~3行内容迁移到8行之后
llllll
llllll
llllll
aaaaaa
aaaaaa
llllll
llllll
llllll
aaaaaa
aaaaaa
aaaaaa
[root@localhost opt]# sed '/the/w ccc.txt' bbb.txt //将包含the 的行另存为文件ccc.txt this is the wood wood wod the wood this is test [root@localhost opt]# cat ccc.txt //查看保存的文件内容 the wood the wood
[root@localhost opt]# sed '/the/r /etc/hostname' bbb.txt this is //将文件/etc/hostname 的内容添加到包含the 的每行以后 the wood localhost.localdomain wood wod the wood localhost.localdomain this is test
[root@localhost opt]# sed '3aNEW' bbb.txt //在第 3 行后插入一个新行,内容为 NEW this is the wood wood NEW wod the wood this is test
[root@localhost opt]# sed '/the/aNEW' bbb.txt //在包含the 的每行后插入一个新行,内容为 NEW this is the wood NEW wood wod the wood NEW this is test
[root@localhost opt]# sed '3aNEW\nNEW2' bbb.txt //在第 3 行后插入多行内容,中间的\n 表示换行 this is the wood wood NEW NEW2 wod the wood this is test
5） 使用脚本编辑文件
- 使用
sed
脚本，将多个编辑指令存放到文件中（每行一条 2272 编辑指令），通过“-f”
选项来调用。
sed '1,3{H;d};6G' bbb.txt //将1~3行的内容迁移到6行之后
[root@localhost opt]# vim test
1,3H
1,3d
6G
~
:wq
[root@localhost opt]# sed -f test bbb.txt
wod
the wood
this is test
this is
the wood
wood
6） sed 直接操作文件示例
- 编写一个脚本，用来调整
vsftpd
服务配置：禁止匿名用户，但允许本地用户（也允许写入）。
[root@localhost ~]# **vim local_only_ftp.sh** #!/bin/bash #指定样本文件路径、配置文件路径 SAMPLE="/usr/share/doc/vsftpd-3.0.2/EXAMPLE/INTERNET_SITE/vsftpd.conf " CONFIG="/etc/vsftpd/vsftpd.conf" #备份原来的配置文件,检测文件名为/etc/vsftpd/vsftpd.conf.bak 备份文件是否存在, 若不存在则使用 cp 命令进行文件备份 [ ! -e "$CONFIG.bak" ] && cp $CONFIG $CONFIG.bak //基于样本配置进行调整,覆盖现有文件 sed -e '/^anonymous_enable/s/YES/NO/g' $SAMPLE > $CONFIG sed -i -e '/^local_enable/s/NO/YES/g' -e '/^write_enable/s/NO/YES/g' $CONFIG grep "listen" $CONFIG || sed -i '$alisten=YES' $CONFIG # 启动vsftpd 服务,并设为开机后自动运行systemctl restart vsftpd systemctl enable vsftpd [root@localhost ~]# **chmod +x local_only_ftp.sh
内容来自用户分享和网络整理，不保证内容的准确性，如有侵权内容，可联系管理员处理 
相关文章推荐
- Shell编程之正则表达式与字符处理
- Shell编程之正则表达式
- shell脚本编程4：正则表达式
- Shell编程之正则表达式
- shell编程之正则表达式
- Shell编程三剑客之grep正则表达式
- shell编程之grep和正则表达式
- #7 shell脚本编程之正则表达式
- shell 编程（一）之 正则表达式
- shell编程之正则表达式
- Linux下shell脚本编程之正则表达式
- shell编程值之正则表达式与字符截取(6)
- shell编程之正则表达式
- 《云计算》shell高级编程-正则表达式
- Shell编程之正则表达式三剑客——sed工具
- linux下shell 编程之扩展正则表达式
- shell编程学习之正则表达式
- shell脚本编程（一）正则表达式
- Shell编程之正则表达式
- shell编程之正则表达式