1、显示/boot/grub/grub.conf中以至少一个空白字符开头的行；
[[email protected] grub]# grep "^[[:space:]]+.*" grub.conf root (hd0,0) 限于格式要求，只截取部分显示结果
2、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；
[[email protected] rc.d]# grep "^#[[:space:]]+[^[:space:]]" 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). # Update quotas if necessary # Check to see if a full relabel is needed # 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 [[email protected] rc.d]#
3、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] rc.d]# netstat -tan | grep "LISTEN[[:space:]]*$" tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN tcp 0 0 :::22 :::* LISTEN tcp 0 0 ::1:631 :::* LISTEN tcp 0 0 ::1:25 :::* LISTEN
4、添加用户bash, testbash, basher, nologin (此一个用户的shell为/sbin/nologin)，而后找出当前系统上其用 户名和默认shell相同的用户的信息；
[[email protected] ~]# grep "^([a-z]+b).*$" /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:501:501::/home/bash:/bin/bash nologin:x:503:503::/home/nologin:/sbin/nologin [[email protected] ~]#
5、显示当前系统上root、fedora或user1用户的默认shell；
[[email protected] ~]# grep -E "^(root|fedora|user1)b.*" /etc/passwd | cut -d: -f1,7 root:/bin/bash fedora:/bin/bash user1:/bin/bash [[email protected] ~]#
6、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()；
[[email protected] ~]# grep "[[:alnum:]]+()" /etc/rc.d/init.d/functions fstab_decode_str() { checkpid() { __readlink() { __fgrep() { __umount_loop() { __umount_loopback_loop() { __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() { confirm() { get_numeric_dev() { is_ignored_file() { is_true() { is_false() { apply_sysctl() { key_is_random() { find_crypto_mount_point() { init_crypto() { [[email protected] ~]#
7、使用echo命令输出一个绝对路径，使用grep取出其基名；
[[email protected] ~]# echo /tmp/test/ | grep -o "[^/]+/?$" test/ 扩展：取出其路径名 [[email protected] ~]# echo /tmp/test/ | grep -o "^/+[[:alnum:]]+b" /tmp
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