grep的用法
1、復制/etc/skel目錄為/home/tuser1及其內容文件的屬組和其它用戶均沒有任何訪問權限。
cp -R /etc/skel /home/thuser1 #復制文件/etc/skel 到/home/目錄下并改名為thuser1
chmod -R 700 /home/thuser1 #更改/home/thuser1目錄權限為屬主全部權限，屬組和其他用戶則沒有任何權限
[root@localhost ~]# cp -R /etc/skel /home/thuser1 [root@localhost ~]# ls /home/thuser1 -ld drwxr-xr-x. 3 root root 78 Jul 23 04:40 /home/thuser1 [root@localhost ~]# chmod -R 700 /home/thuser1 [root@localhost ~]# ls /home/thuser1 -ld drwx------. 3 root root 78 Jul 23 04:40 /home/thuser1 [root@localhost ~]#
2、編輯/etc/group文件，添加組hadoop。
echo hadoop:x:300 >> /etc/group #將顯示的字符串疊加導入到/etc/passwd里
[root@localhost ~]# echo hadoop:x:300 >> /etc/group [root@localhost ~]# [root@localhost ~]# tail -1 /etc/group hadoop:x:300 [root@localhost ~]#
3、手動編輯/etc/passwd文件新增一行，添加用戶hadoop，其基本組ID 為hadoop組的id號；其家目錄為/home/dadoop。
echo hadoop:x:300:300:/home/hadoop:bin/bash >> /etc/passwd
[root@localhost ~]# echo hadoop:x:300:300:/home/hadoop:bin/bash >> /etc/passwd [root@localhost ~]# [root@localhost ~]# [root@localhost ~]# tail -1 /etc/passwd hadoop:x:300:300:/home/hadoop:bin/bash [root@localhost ~]#
4、復制/etc/skel目錄為/home/hadoop，要求修改hadoop目錄的屬組和其他用戶沒有任何訪問權限。
cp -R /etc/skel /home/hadoop #復制文件/etc/skel 到/home/目錄下并改名為hadoop
chmod 700 /home/hadoop/ #更改/home/hadoop目錄權限為屬主全部權限，屬組和其他用戶則沒有任何權限
[root@localhost ~]# cp -R /etc/skel /home/hadoop [root@localhost ~]# ls /home/hadoop/ -ld drwxr-xr-x. 4 root root 90 Jul 23 05:05 /home/hadoop/ [root@localhost ~]# [root@localhost ~]# chmod 700 /home/hadoop/ [root@localhost ~]# ls /home/hadoop/ -ld drwx------. 4 hadoop hadoop 90 Jul 23 05:05 /home/hadoop/ [root@localhost ~]#
5、修改/home/hadoop目錄及其它內部所有文件的屬主問hadoop，屬組為hadoop。
chown hadoop:hadoop /home/hadoop #修改/home/hadoop目錄屬主屬組為hadoop
[root@localhost ~]# chown hadoop:hadoop /home/hadoop [root@localhost ~]# ls /home/hadoop/ -ld drwxr-xr-x. 4 hadoop hadoop 90 Jul 23 05:05 /home/hadoop/ [root@localhost ~]#
6、顯示/proc/meminfo文件中以大寫S開頭的行；用兩種方式。
Method 1
cat /proc/meminfo |grep ‘^S’ #查看/proc/meminfo文件，并搜索以大寫‘S’開頭的行
[root@localhost ~]# cat /proc/meminfo | grep '^S' SwapCached: 0 kB SwapTotal: 2097148 kB SwapFree: 2097148 kB Shmem: 10568 kB Slab: 113956 kB SReclaimable: 55908 kB SUnreclaim: 58048 kB [root@localhost ~]#
Method 2
grep -E ‘^(S)’ /proc/meminfo
[root@localhost ~]# grep -E '^(S)' /proc/meminfo SwapCached: 0 kB SwapTotal: 2097148 kB SwapFree: 2097148 kB Shmem: 10568 kB Slab: 113956 kB SReclaimable: 55908 kB SUnreclaim: 58048 kB [root@localhost ~]#
7、顯示/etc/passwd文件中其默認shell為非/sbin/nologin的用戶；
grep -v ‘/sbin/nologin’ /etc/passwd |cut -d’:’ -f1 #顯示非/sbin/nologin 的行，再搜索一‘：’為分隔符的第一個字段
[root@localhost ~]# grep -v '/sbin/nologin' /etc/passwd |cut -d':' -f1 root sync shutdown halt danry hadoop [root@localhost ~]#
8、顯示/etc/passwd文件中其默認shell為/bin/bash的用戶；
[root@localhost ~]# grep '/bin/bash' /etc/passwd root:x:0:0:root:/root:/bin/bash danry:x:1000:1000:danry:/home/danry:/bin/bash [root@localhost ~]#
9、找出/etc/passwd文件中的一位數或兩位數；
[root@localhost ~]# grep -E "\<[0-9]{1,2}\>" /etc/passwd
root:x:0:0:root:/root:/bin/bash
bin:x:1:1:bin:/bin:/sbin/nologin
daemon:x:2:2:daemon:/sbin:/sbin/nologin
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/sbin/nologin
sync:x:5:0:sync:/sbin:/bin/sync
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
ftp:x:14:50:FTP User:/var/ftp:/sbin/nologin
nobody:x:99:99:Nobody:/:/sbin/nologin
dbus:x:81:81:System message bus:/:/sbin/nologin
tss:x:59:59:Account used by the trousers package to sandbox the tcsd daemon:/dev/null:/sbin/nologin
rpc:x:32:32:Rpcbind Daemon:/var/lib/rpcbind:/sbin/nologin
saslauth:x:994:76:Saslauthd user:/run/saslauthd:/sbin/nologin
rpcuser:x:29:29:RPC Service User:/var/lib/nfs:/sbin/nologin
radvd:x:75:75:radvd user:/:/sbin/nologin
ntp:x:38:38::/etc/ntp:/sbin/nologin
gdm:x:42:42::/var/lib/gdm:/sbin/nologin
sshd:x:74:74:Privilege-separated SSH:/var/empty/sshd:/sbin/nologin
avahi:x:70:70:Avahi mDNS/DNS-SD Stack:/var/run/avahi-daemon:/sbin/nologin
postfix:x:89:89::/var/spool/postfix:/sbin/nologin
tcpdump:x:72:72::/:/sbin/nologin
[root@localhost ~]# ^C
10、顯示/boot/grub/grub.conf中以至少一個空白字符開頭的行；
[root@localhost ~]# grep '^ ' /boot/grub2/grub.cfg
load_env
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
set default="${saved_entry}"
menuentry_id_option="--id"
menuentry_id_option=""
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
set timeout_style=menu
set timeout=5
set timeout=5
source ${prefix}/user.cfg
if [ -n "${GRUB2_PASSWORD}" ]; then
set superusers="root"
export superusers
password_pbkdf2 root ${GRUB2_PASSWORD}
fi
source ${config_directory}/custom.cfg
source $prefix/custom.cfg;
[root@localhost ~]#
11、顯示/etc/rc.d/rc.sysinit文件中以#號開頭，后面跟至少一個空白字符，而后面至少一個非空白字符的行；
[root@localhost ~]# grep -E '^#[[:space:]]+[^spance:]+' /etc/rc.d/rc.local # THIS FILE IS ADDED FOR COMPATIBILITY PURPOSES # It is highly advisable to create own systemd services or udev rules # to run scripts during boot instead of using this file. # In contrast to previous versions due to parallel execution during boot # this script will NOT be run after all other services. # Please note that you must run 'chmod +x /etc/rc.d/rc.local' to ensure # that this script will be executed during boot. [root@localhost ~]#
12、打出netstat -tan命令執行結果中以‘LISTEN’，后跟空白字符行；
[root@localhost ~]# netstat -tan |grep "LISTEN"' '*$ tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN tcp6 0 0 :::111 :::* LISTEN tcp6 0 0 :::22 :::* LISTEN tcp6 0 0 ::1:631 :::* LISTEN tcp6 0 0 ::1:25 :::* LISTEN [root@localhost ~]#
13、添加用戶bash，testbash，basher，nologin（此一個用戶的shell為/sbin/nologin），然后找出當前系統上其用戶名和默認shell相同的用用戶的信息；
[root@localhost ~]# grep -E "^(\<[[:alnum:]]+\>).*\1$" /etc/passwd sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt bash:x:3007:3008::/home/bash:/bin/bash nologin:x:3010:3011::/home/nologin:/sbin/nologin [root@localhost ~]# grep "^\([[:alnum:]]\+\>\).*\1$" /etc/passwd sync:x:5:0:sync:/sbin:/bin/sync shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown halt:x:7:0:halt:/sbin:/sbin/halt bash:x:3007:3008::/home/bash:/bin/bash nologin:x:3010:3011::/home/nologin:/sbin/nologin
原創文章，作者：N27_Danry，如若轉載，請注明出處：http://www.www58058.com/82497
注意下第五題、第十一題，答題還需要再仔細，繼續加油~