sed结合正则表达式强化练习

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、删除/etc/grub2.conf文件中所有以空白开头的行行首的空白字符

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[iyunv@centos7 ~]# sed -r 's#^[[:space:]]+##g' /etc/grub2.cfg # # DO NOT EDIT THIS FILE # # It is automatically generated by grub2-mkconfig using templates # from /etc/grub.d and settings from /etc/default/grub # ### BEGIN /etc/grub.d/00_header ### set pager=1 if [ -s $prefix/grubenv ]; then load_env fi if [ "${next_entry}" ] ; then set default="${next_entry}" set next_entry= save_env next_entry set boot_once=true else set default="${saved_entry}" fi if [ x"${feature_menuentry_id}" = xy ]; then menuentry_id_option="--id" else menuentry_id_option="" fi export menuentry_id_option if [ "${prev_saved_entry}" ]; then set saved_entry="${prev_saved_entry}" save_env saved_entry set prev_saved_entry= save_env prev_saved_entry set boot_once=true fi

2、删除/etc/fstab文件中所有以#开头，后面至少跟一个空白字符的行的行首的#和空白字符

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[iyunv@centos7 ~]# sed -r 's/^#[[:space:]]+//g' /etc/fstab # /etc/fstab Created by anaconda on Tue Jul 19 14:39:24 2016 # Accessible filesystems, by reference, are maintained under '/dev/disk' See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # UUID=f83c52ce-5740-4f02-bb87-6e190360dc30 /                       xfs     defaults  0 0 UUID=c98144e4-d1b4-45b1-bb22-3112420ea487 /boot                   xfs     defaults  0 0 UUID=dbf5c483-133e-4888-bbb1-a9622d83a930 swap                    swap    defaults  0 0 #END [iyunv@centos7 ~]#

2.1、删除/etc/fstab文件中所有以#开头，后面至少跟一个空白字符的行的行首的#和空白字符且删除以#开头后面全是空白字符的行

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[iyunv@centos7 ~]# sed -r -e 's/^#[[:space:]]+//g' -e '/^#/d' /etc/fstab /etc/fstab Created by anaconda on Tue Jul 19 14:39:24 2016 Accessible filesystems, by reference, are maintained under '/dev/disk' See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info UUID=f83c52ce-5740-4f02-bb87-6e190360dc30 /                       xfs     defaults  0 0 UUID=c98144e4-d1b4-45b1-bb22-3112420ea487 /boot                   xfs     defaults  0 0 UUID=dbf5c483-133e-4888-bbb1-a9622d83a930 swap                    swap    defaults  0 0 [iyunv@centos7 ~]#

3、在/etc/issue每一行行首增加#号

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[iyunv@centos7 ~]# cat -n /etc/issue      1\S      2Kernel \r on an \m      3 [iyunv@centos7 ~]# sed -r 's@(.*)@#&@g' /etc/issue #\S #Kernel \r on an \m # [iyunv@centos7 ~]# sed -r 's@(.*)@#\1@g' /etc/issue #\S #Kernel \r on an \m # [iyunv@centos7 ~]# sed -r 's@^@#@g' /etc/issue #\S #Kernel \r on an \m # [iyunv@centos7 ~]#

4、在/etc/fstab文件中不以#开头的行的行首增加#号

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[iyunv@centos7 ~]# sed -r 's/^[^#]/#/g' /etc/fstab # # /etc/fstab # Created by anaconda on Tue Jul 19 14:39:24 2016 # # Accessible filesystems, by reference, are maintained under '/dev/disk' # See man pages fstab(5), findfs(8), mount(8) and/or blkid(8) for more info # #UID=f83c52ce-5740-4f02-bb87-6e190360dc30 /                       xfs     defaults #UID=c98144e4-d1b4-45b1-bb22-3112420ea487 /boot                   xfs     defaults #UID=dbf5c483-133e-4888-bbb1-a9622d83a930 swap                    swap    defaults #END [iyunv@centos7 ~]#

5、处理/etc/fstab路径,使用sed命令取出其目录名和基名

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[iyunv@centos7 Packages]# cd [iyunv@centos7 ~]# echo "/etc/hosts"|sed -r 's#/.*/([^/]+)#\1#g' hosts [iyunv@centos7 ~]# echo "/etc/hosts" |sed -r 's#(/.*/)[^/]+/?#\1#g' /etc/ [iyunv@centos7 ~]# echo "/etc/issue"|sed -r 's#(.*/)([^/]+/?)$#\1#g' /etc/ [iyunv@centos7 ~]# echo "/etc/issue"|sed -r 's#(.*/)([^/]+/?)$#\2#g' issue [iyunv@centos7 ~]#

6、利用sed 取出ifconfig命令中本机的IPv4地址

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[iyunv@centos7 ~]# ifconfig |sed -n 2p         inet 192.168.226.138  netmask 255.255.255.0  broadcast 192.168.226.255 [iyunv@centos7 ~]# ifconfig |sed -n 2p|sed -r 's/.*net //g' 192.168.226.138  netmask 255.255.255.0  broadcast 192.168.226.255 [iyunv@centos7 ~]# ifconfig |sed -n 2p|sed -r 's/.*net //g'|sed -r 's/  net.*//g' 192.168.226.138 [iyunv@centos7 ~]# ifconfig |sed -nr '2s#^.*net (.*)  netm.*$#\1#gp' 192.168.226.138 [iyunv@centos7 ~]#

7、统计centos安装光盘中Package目录下的所有rpm文件的 以.分隔倒数第二个字段的重复次数

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[iyunv@centos7 Packages]# ls *.rpm |sed -r 's/^.*\.(.*)\.rpm/\1/g'|sort |uniq -c |sort    2000 i686    2938 noarch    4069 x86_64 [iyunv@centos7 Packages]# ls *.rpm |rev |cut -d. -f2 |sort|uniq -c|uniq    4069 46_68x    2000 686i    2938 hcraon [iyunv@centos7 Packages]#