23、grep/egrep正則表達式練習：

1) 顯示/etc/passwd文件中不以bash結尾的行；

答：

# grep -v "bash$" /etc/passwd

2) 找出ifconfig命令執行結果中的兩位或三位整數；

答：

# ifconfig | grep --color=auto "\<\([[:digit:]]\{2,3\}\)\>" //還有00

# ifconfig | grep --color=auto "\<\([1-9][0-9]\|[1-9][0-9][0-9]\)\>" //完美

3) 找出/etc/grub2.cfg(在CentOS6中是/etc/grub.conf)文件中，以空白字符開頭的非空白行；

答：

# cat /etc/grub.conf | grep "^[[:space:]]\+.*[^[:space:]]$" //centos6

# grep "^[[:space]]\+[^[:space:]]\+" /etc/grub2.cfg //centos7

default=0

設定默認啟動菜單項；整個菜單中的所有的title是從0開始編號的；

timeout=5

用戶未作出選擇時，grub會自動引導默認菜單對應的內核的超時時間；

splashimage=(hd0,0)/grub/splash.xpm.gz

grub的背景圖片對應的路徑；

hiddenmenu

隱藏grub的啟動菜單

password --md5 CRYPTED_PASSWORD

為了保護菜單設置的密碼，通常用於防止隨意進入單用戶模式；

title CentOS 6 (2.6.32-573.el6.x86_64)

定義菜單項中的各個"標題"，可以定義多個title項；至少有一項；

root (hd0,0)

指定grub的根設備，通常是用來安裝grub的那個分區；

kernel /vmlinuz-2.6.32-573.el6.x86_64 ro root=UUID=5ebb0e76-bb19-4a80-9c70-0d101c0778e1 nomodeset rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet

該菜單對應的要啟動的內核及傳遞給內核的各個參數；

initrd /initramfs-2.6.32-573.el6.x86_64.img

內核所對應的ramdisk(ramfs)文件

password --md5 CRYPTED_PASSWORD

保護操作系統內核的啟動；

4) 找出"netstat -tan”命令的結果中，以"LISTEN"後跟任意個空白字符結尾的行；

答：

# netstat -tan | grep ".*LISTEN[[:space:]]*$"

# netstat -tan | grep "LISTEN[[:space:]]*$"

5) 找出"fdisk -l"命令的結果中，包含以/dev/後跟sd或hd及一個小寫字母的行；

答：

# fdisk -l | grep "^/dev/[s|h]d[a-z]"

6) 找出"ldd /usr/bin/vim"命令的結果中所有的文件路徑；

答：

# ldd /usr/bin/vim | grep -o "/[^[:space:]]\+"

# ldd /usr/bin/vim | grep -o "/.*/.*"

7) 找出/proc/meminfo文件中，所有以大寫S或小寫s開頭的行，你有多少種方法實現該任務？

答：

# cat /proc//meminfo | grep "^[Ss].*" //內存使用情況

# cat /proc//meminfo | grep -E "^(S|s).*"

# cat /proc//meminfo | grep -i "^s" //忽略大小寫

# cat /proc/meminfo | grep "^s\|^S" //註意解釋輸出“或”

# cat /proc/meminfo | grep -e "^s" -e "^S" //多項匹配

8) 使用egrep取出某個路徑的基名；

答：

# ls /usr/bin/ldd | grep -o "/[a-z]\+$"

9) 顯示出ifconfig命令結果中的0-255之間的整數；

答：

# ifconfig | grep --color=auto "\<\([0-9]\|[1-9][0-9]\|1[0-9][0-9]\|2[0-4][0-9]\|25[0-5]\)\>"

10) 添加用戶bash, testbash, basher, nologin, unlogin, logining，要求前三個用戶的默認shell為/bin/bash，後三個用戶的默認shell為/sbin/nologin，而後找出其用戶名與shell名相同的用戶信息；

答：

# useradd -s /bin/bash bash

# useradd -s /bin/bash basher

# useradd -s /bin/bash testbash

# useradd -s /sbin/nologin nologin

# useradd -s /sbin/nologin unlogin

# useradd -s /sbin/nologin logining //創建多用戶可用腳本來完成

# cat /etc/passwd | grep "^\<\([[:alnum:]]\+\)\>.*\1$"

例：

[root@little ~]# grep -v "bash$" /etc/passwd

bin:x:1:1:bin:/bin:/sbin/nologin

daemon:x:2:2:daemon:/sbin:/sbin/nologin

……

[root@little ~]# ifconfig | grep --color=auto "\<\([[:digit:]]\{2,3\}\)\>"

eth0 Link encap:Ethernet HWaddr 00:0C:29:EF:91:5E

inet addr:172.16.67.2 Bcast:172.16.255.255 Mask:255.255.0.0

inet6 addr: fe80::20c:29ff:feef:915e/64 Scope:Link

RX bytes:638912 (623.9 KiB) TX bytes:587812 (574.0 KiB)

eth1 Link encap:Ethernet HWaddr 00:0C:29:EF:91:68

inet addr:192.168.222.136 Bcast:192.168.222.255 Mask:255.255.255.0

inet6 addr: fe80::20c:29ff:feef:9168/64 Scope:Link

TX packets:11 errors:0 dropped:0 overruns:0 carrier:0

RX bytes:112446 (109.8 KiB) TX bytes:1334 (1.3 KiB)

eth2 Link encap:Ethernet HWaddr 00:0C:29:EF:91:72

inet addr:192.168.222.137 Bcast:192.168.222.255 Mask:255.255.255.0

inet6 addr: fe80::20c:29ff:feef:9172/64 Scope:Link

TX packets:175 errors:0 dropped:0 overruns:0 carrier:0

RX bytes:120635 (117.8 KiB) TX bytes:17648 (17.2 KiB)

inet addr:127.0.0.1 Mask:255.0.0.0

inet6 addr: ::1/128 Scope:Host

RX packets:46 errors:0 dropped:0 overruns:0 frame:0

TX packets:46 errors:0 dropped:0 overruns:0 carrier:0

[root@little ~]#

[root@little ~]# cat /etc/grub.conf

# grub.conf generated by anaconda

#

# Note that you do not have to rerun grub after making changes to this file

# NOTICE: You have a /boot partition. This means that

# all kernel and initrd paths are relative to /boot/, eg.

# root (hd0,0)

# kernel /vmlinuz-version ro root=/dev/sda2

# initrd /initrd-[generic-]version.img

#boot=/dev/sda1

default=0

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title CentOS 6 (2.6.32-573.el6.x86_64)

root (hd0,0)

kernel /vmlinuz-2.6.32-573.el6.x86_64 ro root=UUID=1e8379ed-1b71-4c70-b97a-4d2121654719 nomodeset rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet

initrd /initramfs-2.6.32-573.el6.x86_64.img

[root@little ~]#

[root@little ~]# cat /etc/grub.conf | grep "^[[:space:]]\+.*[^[:space:]]$"

root (hd0,0)

kernel /vmlinuz-2.6.32-573.el6.x86_64 ro root=UUID=1e8379ed-1b71-4c70-b97a-4d2121654719 nomodeset rd_NO_LUKS KEYBOARDTYPE=pc KEYTABLE=us rd_NO_MD crashkernel=auto LANG=zh_CN.UTF-8 rd_NO_LVM rd_NO_DM rhgb quiet

initrd /initramfs-2.6.32-573.el6.x86_64.img

[root@little ~]#

[root@little ~]# netstat -tan | grep ".*LISTEN[[:space:]]*$"

tcp 0 0 0.0.0.0:36239 0.0.0.0:* LISTEN

tcp 0 0 0.0.0.0:111 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

tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN

tcp 0 0 :::111 :::* LISTEN

tcp 0 0 :::80 :::* LISTEN

tcp 0 0 :::33813 :::* LISTEN

tcp 0 0 :::22 :::* LISTEN

tcp 0 0 ::1:631 :::* LISTEN

tcp 0 0 ::1:25 :::* LISTEN

tcp 0 0 ::1:6010 :::* LISTEN

[root@little ~]#

[root@little ~]# fdisk -l | grep "^/dev/[s|h]d[a-z]"

/dev/sda1 * 1 26 204800 83 Linux

/dev/sda2 26 6553 52428800 83 Linux

/dev/sda3 6553 6814 2097152 82 Linux swap / Solaris

[root@little ~]#

[root@little ~]# ldd /usr/bin/vim | grep -o "/.*/.*"

/lib64/libm.so.6 (0x0000003634800000)

/lib64/libselinux.so.1 (0x0000003635400000)

/lib64/libtinfo.so.5 (0x000000363d000000)

/lib64/libacl.so.1 (0x0000003c76800000)

/usr/lib64/libgpm.so.2 (0x0000003634c00000)

/usr/lib64/perl5/CORE/libperl.so (0x0000003634400000)

/lib64/libdl.so.2 (0x0000003633800000)

/lib64/libpthread.so.0 (0x0000003634000000)

/lib64/libc.so.6 (0x0000003633c00000)

/lib64/ld-linux-x86-64.so.2 (0x0000003633400000)

/lib64/libattr.so.1 (0x0000003643800000)

/lib64/libresolv.so.2 (0x0000003635800000)

/lib64/libnsl.so.1 (0x0000003644c00000)

/lib64/libcrypt.so.1 (0x000000363f800000)

/lib64/libutil.so.1 (0x0000003643c00000)

/lib64/libfreebl3.so (0x000000363f400000)

[root@little ~]#

[root@little ~]# ldd /usr/bin/vim | grep -o "/[^[:space:]]\+"

/lib64/libm.so.6

/lib64/libselinux.so.1

/lib64/libtinfo.so.5

/lib64/libacl.so.1

/usr/lib64/libgpm.so.2

/usr/lib64/perl5/CORE/libperl.so

/lib64/libdl.so.2

/lib64/libpthread.so.0

/lib64/libc.so.6

/lib64/ld-linux-x86-64.so.2

/lib64/libattr.so.1

/lib64/libresolv.so.2

/lib64/libnsl.so.1

/lib64/libcrypt.so.1

/lib64/libutil.so.1

/lib64/libfreebl3.so

[root@little ~]#

[root@little ~]# ldd /usr/bin/vim | grep -o "/[^[:space:]]\+" | wc -l

16

[root@little ~]# ldd /usr/bin/vim | grep -o "/.*/.*" | wc -l

16

[root@little ~]# cat /proc//meminfo | grep "^[S|s].*"

SwapCached: 48 kB

SwapTotal: 2097148 kB

SwapFree: 2094960 kB

Shmem: 3136 kB

Slab: 85056 kB

SReclaimable: 15576 kB

SUnreclaim: 69480 kB

[root@little ~]# ls /usr/bin/ldd | grep -o "/[a-z]\+$"

/ldd

[root@little ~]#

[root@little ~]# ifconfig | grep --color=auto "\<\([0-9]\|[1-9][0-9]\|1[0-9][0-9]\|2[0-4][0-9]\|25[0-5]\)\>"

[root@little ~]#

[root@little ~]# cat /etc/passwd | grep "^\<\([[:alnum:]]\+\)\>.*\1$"

sync:x:5:0:sync:/sbin:/bin/sync

shutdown:x:6:0:shutdown:/sbin:/sbin/shutdown

halt:x:7:0:halt:/sbin:/sbin/halt

[root@little ~]#

24.腳本練習：

1) 編寫一個腳本，要求：

統計/etc, /var, /usr目錄中所有非隱藏的一級子目錄和文件的數量總和；

答：

#!/bin/bash

#

a=$(ls /etc | wc -l)

b=$(ls /var | wc -l)

c=$(ls /usr | wc -l)

count=$[$a+$b+$c]

echo "$count"

[root@little ~]# vi 24p1.sh

[root@little ~]#

[root@little ~]# chmod +x 24p1.sh

[root@little ~]#

[root@little ~]# ./24p1.sh

303

2) 編寫一個腳本，要求：

對於目錄/tmp/testdir1，如果當前有效用戶有讀、寫和執行的權限，那麽就在該目錄中創建一個文件；否則，顯示“沒有權限不能創建文件”的信息。

答：

#!/bin/bash

#

FPATH=/tmp/testdir1

[ -r $FPATH -a -w $FPATH -a -x $FPATH ] && touch $FPATH/newdir || echo "Don‘t right to create useradd"

[root@little ~]# vi 24p2.sh

[root@little ~]#

[root@little ~]# ll /tmp/testdir1

total 0

[root@little ~]# chmod +x 24p

24p1.sh 24p2.sh

[root@little ~]# chmod +x 24p2.sh

[root@little ~]#

[root@little ~]# ./24p2.sh

[root@little ~]#

[root@little ~]# ll /tmp/testdir1

total 0

-rw-r--r--. 1 root root 0 Nov 21 11:29 newdir

[root@little ~]#

3) 編寫一個腳本，要求：

從/etc/passwd中UID和GID相同的用戶中隨機選擇一個用戶，判斷其用戶名和基本組名是否相同；

答：

#!/bin/bash

#

username=$(grep "\<\([[:digit:]]\+\).*\1\>" /etc/passwd | sort -R | head -1 | cut -d":" -f1)

groupname=$(id -gn $username)

[ $username == $groupname ] && echo "username and group is same." || "username and groupname is different."

[root@little ~]# vi 24p3.sh

[root@little ~]#

[root@little ~]# chmod +x 24p3.sh

[root@little ~]#

[root@little ~]# ./24p3.sh

cut: invalid option -- ‘1‘

Try `cut --help‘ for more information.

./24p3.sh: line 5: [: ==: unary operator expected

./24p3.sh: line 5: username and groupname is different.: command not found

[root@little ~]#

[root@little ~]# vi +5 24p3.sh

[root@little ~]#

[root@little ~]# ./24p3.sh

username and group is same.

[root@little ~]#

linux-practice(23-24)