1、显示当前系统上root、fedora或user1用户的默认shell;
grep -E “^(root|fedora|user1)>” /etc/passwd | cut -d: -f1,7
[root@bogon Desktop]# grep -E "^(root|fedora|user1)\>" /etc/passwd | cut -d: -f1,7 root:/bin/bash fedora:/bin/bash user1:/bin/bash
2、找出/etc/rc.d/init.d/functions文件中某单词后面跟一组小括号的行，形如：hello()；
grep “[[:alpha:]]+()” /etc/rc.d/init.d/functions
[root@bogon Desktop]# grep "[[:alpha:]]+()" /etc/rc.d/init.d/functions
checkpid() {
__pids_var_run() {
__pids_pidof() {
daemon() {
killproc() {
pidfileofproc() {
pidofproc() {
status() {
echo_success() {
echo_failure() {
echo_passed() {
echo_warning() {
update_boot_stage() {
success() {
failure() {
passed() {
warning() {
action() {
strstr() {
is_ignored_file() {
is_true() {
is_false() {
apply_sysctl() {
3、使用echo命令输出一个绝对路径，使用grep取出其基名；扩展：取出其路径名;
echo /etc/passwd | grep -o “[^/]+/\?$” passwd
[root@bogon ~]# echo /etc/passwd | grep -o "[^/]\+/\?$" passwd [root@bogon ~]#
echo /etc/passwd | grep -oP ‘/.*/(?=.?\b)’
[root@bogon ~]# echo /etc/passwd | grep -oP '/.*/(?=.?\b)' /etc/ [root@bogon ~]#
4、找出ifconfig命令结果中的1-255之间数字；
ifconfig | grep -E ‘\<([0-9]|([0-9][0-9])|(1[0-9][0-9])|(2[1-4][0-9])|(25[1-5]))>’
[root@bogon ~]# ifconfig | grep -E '\<([0-9]|([0-9][0-9])|(1[0-9][0-9])|(2[1-4][0-9])|(25[1-5]))\>'
inet 192.168.101.15 netmask 255.255.255.0 broadcast 192.168.101.255
inet6 fe80::20c:29ff:fe00:b610 prefixlen 64 scopeid 0x20<link>
ether 00:0c:29:00:b6:10 txqueuelen 1000 (Ethernet)
RX packets 90557 bytes 114145934 (108.8 MiB)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 32344 bytes 15212308 (14.5 MiB)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo: flags=73<UP,LOOPBACK,RUNNING> mtu 65536
inet 127.0.0.1 netmask 255.0.0.0
inet6 ::1 prefixlen 128 scopeid 0x10<host>
loop txqueuelen 0 (Local Loopback)
RX packets 4 bytes 340 (340.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 4 bytes 340 (340.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
inet 192.168.122.1 netmask 255.255.255.0 broadcast 192.168.122.255
ether 00:00:00:00:00:00 txqueuelen 0 (Ethernet)
RX packets 0 bytes 0 (0.0 B)
RX errors 0 dropped 0 overruns 0 frame 0
TX packets 0 bytes 0 (0.0 B)
TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
[root@bogon ~]#
5、挑战题：写一个模式，能匹配合理的IP地址；
ifconfig | grep -o -E “(([0-9]|[0-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5]).){3}([0-9]|[0-9][0-9]|1[0-9])”
[root@bogon ~]# ifconfig | grep -o -E "(([0-9]|[0-9][0-9]|1[0-9][0-9]|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[0-9][0-9]|1[0-9])"
192.168.101.15
255.255.255.0
192.168.101.25
127.0.0.1
255.0.0.0
192.168.122.1
255.255.255.0
192.168.122.25
[root@bogon ~]#
6、挑战题：写一个模式，能匹配出所有的邮件地址；
grep -E “([[:alph^C]]|[0-9]|[[:punct:]]*|.|\@)”
7、查找/var目录下属主为root，且属组为mail的所有文件或目录；
find /var/ -user root -group mail -ls
[root@bogon ~]# find /var/ -user root -group mail -ls 100664302 4 drwxrwxr-x 2 root mail 4096 Aug 2 22:57 /var/spool/mail [root@bogon ~]#
8、查找当前系统上没有属主或属组的文件；
find / -nouser -nogroup -ls
[root@bogon ~]# find / -nouser -nogroup -ls find: ‘/proc/11927/task/11927/fd/6’: No such file or directory find: ‘/proc/11927/task/11927/fdinfo/6’: No such file or directory find: ‘/proc/11927/fd/6’: No such file or directory find: ‘/proc/11927/fdinfo/6’: No such file or directory find: ‘/run/user/1000/gvfs’: Permission denied 137 0 drwxr-xr-x 2 2006 2006 6 Aug 3 20:44 /root/abc 35461830 0 drwxr-xr-x 2 2006 2006 6 Aug 3 20:44 /root/asdf 68898945 0 drwx------ 3 2006 2006 74 Aug 3 20:44 /home/qqq 102702695 0 drwxr-xr-x 4 2006 2006 37 Jul 11 07:27 /home/qqq/.mozilla 1622887 0 drwxr-xr-x 2 2006 2006 6 Jun 9 2014 /home/qqq/.mozilla/extensions 35461829 0 drwxr-xr-x 2 2006 2006 6 Jun 9 2014 /home/qqq/.mozilla/plugins 68898946 4 -rw-r--r-- 1 2006 2006 18 Nov 20 2015 /home/qqq/.bash_logout 68898949 4 -rw-r--r-- 1 2006 2006 193 Nov 20 2015 /home/qqq/.bash_profile 68898950 4 -rw-r--r-- 1 2006 2006 231 Nov 20 2015 /home/qqq/.bashrc [root@bogon ~]#
9、查找/etc目录下所有用户都有写权限的文件；
find /etc -prem -222 -ls
[root@bogon ~]# find /etc/ -perm -222 -ls 33790768 0 lrwxrwxrwx 1 root root 10 Jul 11 07:27 /etc/rc6.d -> rc.d/rc6.d 100801421 0 lrwxrwxrwx 1 root root 16 Jul 11 07:27 /etc/ssl/certs -> ../pki/tls/certs 36511098 0 lrwxrwxrwx 1 root root 38 Jul 11 07:36 /etc/localtime -> ../usr/share/zoneinfo/America/New_York 33902848 0 lrwxrwxrwx 1 root root 56 Jul 11 07:27 /etc/favicon.png -> /usr/share/icons/hicolor/16x16/apps/fedora-logo-icon.png 34570567 0 lrwxrwxrwx 1 root root 25 Jul 11 07:32 /etc/pam.d/smtp -> /etc/alternatives/mta-pam 33904308 0 lrwxrwxrwx 1 root root 14 Jul 11 07:36 /etc/pam.d/system-auth -> system-auth-ac 33904306 0 lrwxrwxrwx 1 root root 12 Jul 11 07:36 /etc/pam.d/postlogin -> postlogin-ac 33904305 0 lrwxrwxrwx 1 root root 16 Jul 11 07:36 /etc/pam.d/password-auth -> password-auth-ac 33904303 0 lrwxrwxrwx 1 root root 19 Jul 11 07:36 /etc/pam.d/fingerprint-auth -> fingerprint-auth-ac 33904307 0 lrwxrwxrwx 1 root root 17 Jul 11 07:36 /etc/pam.d/smartcard-auth -> smartcard-auth-ac 1660802 0 lrwxrwxrwx 1 root root 14 Jul 11 07:29 /etc/libvirt/qemu/networks/autostart/default.xml -> ../default.xml 34181389 0 lrwxrwxrwx 1 root root 19 Aug 1 21:15 /etc/httpd/logs -> ../../var/log/httpd 34181390 0 lrwxrwxrwx 1 root root 29 Aug 1 21:15 /etc/httpd/modules -> ../../usr/lib64/httpd/modules 34181391 0 lrwxrwxrwx 1 root root 10 Aug 1 21:15 /etc/httpd/run -> /run/httpd 101468179 0 lrwxrwxrwx 1 root root 35 Jul 11 07:32 /etc/cifs-utils/idmap-plugin -> /etc/alternatives/cifs-idmap-plugin 71753217 0 lrwxrwxrwx 1 root root 21 Jul 11 07:31 /etc/gdm/Xsession -> ../X11/xinit/Xsession 33556151 0 lrwxrwxrwx 1 root root 22 Jul 11 07:32 /etc/grub2.cfg -> ../boot/grub2/grub.cfg 36134996 0 lrwxrwxrwx 1 root root 8 Jul 11 07:32 /etc/scl/conf -> prefixes
10、查找/etc目录下大于1M，且类型为普通文件的所有文件；
find /etc -size +1M -ls
[root@bogon ~]# find /etc/ -size +1M -ls 72502453 3772 -rw-r--r-- 1 root root 3858924 Nov 20 2015 /etc/selinux/targeted/policy/policy.29 36328392 6852 -r--r--r-- 1 root root 7014922 Jul 11 07:37 /etc/udev/hwdb.bin 101554968 1336 -rw-r--r-- 1 root root 1367395 Mar 5 2015 /etc/brltty/zh-tw.ctb [root@bogon ~]#
原创文章，作者：N27_Danry，如若转载，请注明出处：http://www.178linux.com/83620
