Linux基础知识四
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1、复制/etc/skel目录为/home/tuser1，要求/home/tuser1及其内部文件的属组和其它用户均没有任何访问权限。
[[email protected] ~]# cp -a /etc/skel /home/tuser1/ [[email protected] ~]# chmod -R go-rwx /home/tuser1/
2、编辑/etc/group文件，添加组hadoop。
[[email protected] ~]# echo "hadoop:x:3007:" >> /etc/group
3、手动编辑/etc/passwd文件新增一行，添加用户hadoop，其基本组ID为hadoop组的id号；其家目录为/home/hadoop。
[[email protected] ~]# echo "hadoop:x:3007:3007::/home/hadoop:/sbin/nologin" >> /etc/passwd [[email protected] ~]# id hadoop uid=3007(hadoop) gid=3007(hadoop) groups=3007(hadoop)
4、复制/etc/skel目录为/home/hadoop，要求修改hadoop目录的属组和其它用户没有任何访问权限。
[[email protected] ~]# cp -a /etc/skel /home/hadoop [[email protected] hadoop]# chmod -R go-rwx /home/hadoop
5、修改/home/hadoop目录及其内部所有文件的属主为hadoop，属组为hadoop。
[[email protected] hadoop]# chown -R hadoop:hadoop /home/hadoop [[email protected] hadoop]# ls -al total 16 drwx------. 3 hadoop hadoop 74 Jun 8 22:35 . drwxr-xr-x. 15 root root 4096 Aug 28 10:44 .. -rw-------. 1 hadoop hadoop 18 Nov 20 2015 .bash_logout -rw-------. 1 hadoop hadoop 193 Nov 20 2015 .bash_profile -rw-------. 1 hadoop hadoop 231 Nov 20 2015 .bashrc drwx------. 4 hadoop hadoop 37 Jun 8 22:34 .mozilla
6、显示/proc/meminfo文件中以大写或小写S开头的行；用两种方式。
[[email protected] hadoop]# grep -i ‘^s‘ /proc/meminfo SwapCached: 204 kB SwapTotal: 511996 kB SwapFree: 496060 kB Shmem: 3732 kB Slab: 76928 kB SReclaimable: 38064 kB SUnreclaim: 38864 kB [[email protected] hadoop]# grep ‘^[Ss]‘ /proc/meminfo SwapCached: 204 kB SwapTotal: 511996 kB SwapFree: 496060 kB Shmem: 3732 kB Slab: 76928 kB SReclaimable: 38064 kB SUnreclaim: 38864 kB
7、显示/etc/passwd文件中其默认shell为非/sbin/nologin的用户。
[[email protected] hadoop]# cat /etc/passwd | grep -v ":/sbin/nologin$"|cut -d: -f 1 root sync shutdown halt yanlibo bob distro mandriva test1 mageia slackware openstack user1 user2
8、显示/etc/passwd文件中其默认shell为/bin/bash的用户。
[[email protected] hadoop]# cat /etc/passwd | grep ":/bin/bash$"|cut -d: -f 1 root yanlibo bob distro mandriva test1 mageia slackware openstack user1 user2
9、找出/etc/passwd文件中的一位数或两位数。
[[email protected] ~]# grep -oP "\b\d{1,2}\b" /etc/passwd 0 0 1 1 2 2 3 4 4 7 5 0 6 0 7 0 8 12 11 0 12 14 50 99 99 66 65 81 81 59 59 76 32 32 29 29 75 75 42 42 70 70 89 89 74 74 38 38 72 72
10、显示/boot/grub/grub.conf中以至少一个空白字符开头的行(CentOS6)。
[[email protected] ~]# grgrep -P "^\s+" /boot/grub/grub.conf root (hd0,0) kernel /vmlinuz-2.6.32-642.el6.x86_64 ro root=/dev/mapper/vg_centos-lv_root nomodeset rd_NO_LUKS LANG=en_US.UTF-8 rd_LVM_LV=vg_centos/lv_swap rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_centos/lv_root KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet initrd /initramfs-2.6.32-642.el6.x86_64.img
11、显示/etc/rc.d/rc.sysinit文件中以#开头，后面跟至少一个空白字符，而后又有至少一个非空白字符的行(CentOS6)。
[[email protected] ~]# grep -P ‘^#\s+\S+‘ /etc/rc.d/rc.sysinit # /etc/rc.d/rc.sysinit - run once at boot time # Taken in part from Miquel van Smoorenburg‘s bcheckrc. # Check SELinux status # Print a text banner. # Only read this once. # Initialize hardware # Set default affinity # Load other user-defined modules # Load modules (for backward compatibility with VARs) # Configure kernel parameters # Set the hostname. # Sync waiting for storage. # Device mapper & related initialization # Start any MD RAID arrays that haven‘t been started yet # Remount the root filesystem read-write. # Clean up SELinux labels # If relabeling, relabel mount points. # Mount all other filesystems (except for NFS and /proc, which is already # mounted). Contrary to standard usage, # filesystems are NOT unmounted in single user mode. # The ‘no‘ applies to all listed filesystem types. See mount(8). # Check to see if a full relabel is needed # Update quotas if necessary # Initialize pseudo-random number generator # Configure machine if necessary. # Clean out /. # Do we need (w|u)tmpx files? We don‘t set them up, but the sysadmin might... # Clean up /var. # Clean up utmp/wtmp # Clean up various /tmp bits # Make ICE directory # Start up swapping. # Set up binfmt_misc # Boot time profiles. Yes, this should be somewhere else. # Now that we have all of our basic modules loaded and the kernel going, # let‘s dump the syslog ring somewhere so we can find it later # create the crash indicator flag to warn on crashes, offer fsck with timeout # Let rhgb know that we‘re leaving rc.sysinit
12、打出netstat -tan命令执行结果中以‘LISTEN’，后或跟空白字符结尾的行。
[[email protected] ~]# netstat -tan | grep -P "LISTEN\s*$" tcp 0 0 192.168.122.1:53 0.0.0.0:* LISTEN tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN tcp6 0 0 :::22 :::* LISTEN tcp6 0 0 ::1:631 :::* LISTEN tcp6 0 0 ::1:6010 :::* LISTEN
13、添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用户名和默认shell相同的用户的信息。
[[email protected] ~]# useradd bash [[email protected] ~]# useradd testbash [[email protected] ~]# useradd basher [[email protected] ~]# useradd -s /sbin/nologin nologin [[email protected] ~]# grep -P "^(\w+):.*\1$" /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:3008:3008::/home/bash:/bin/bash nologin:x:3011:3011::/home/nologin:/sbin/nologin
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