Some command tips

1.crontab

Crontab-u TOM-E
0 8-20/3 * * 2,4/bin/echo hello for Tom customized a scheduled task, 2 per week, 4 of 8 points to 20 every 3 hours to perform/bin/echo hello
2.authconfig

Authconfig--disableshadow–update Deactivate Shadow
Authconfig--enableshadow–update Enable Shadow
3.gpasswd
-R Delete Group password
-R Lock Group password

Gpasswd–a User Group Add Group members
Gpasswd–d User Group Delete group members
4.SUID 4 S
Let the general user execute some programs, temporarily have the program has permissions, only for "binary files", the directory is invalid
SGID 2 S
Multi-team project development, rarely used in the system
Sbit 1 T
Valid only for directory, invalid for file. In a directory with a bit, if the user has W and x permissions in the directory, then when the user establishes a file or directory under that directory, only the file has the right to delete with root
5.ACL Permissions
Command TUNE2FS adjust and view the file system parameters of Ext2/ext3 file system, under Windows if there is an unexpected power outage, the next boot will generally appear system self-test. The Linux system also has a file system self-test, and it is possible to define self-test cycles and methods by TUNE2FS commands.
-O set or clear default mounted file system options
-L View File system Information
#mkfs. ext3/dev/sdb1 format Disk
#tune2fs –o acl/dev/sdb1 To turn on the disk ACL function
#tune2fs –L/DEV/SDB1 to see if ACL functionality is supported
#mount –o REMOUNT,ACL/DEV/SDB1 for previously mounted partitions
#mount –o acl/dev/sdb1/mnt/sdb1 Specify ACL options
-O Options Specify options
Permanently start ACL, modify/etc/fstab
/DEV/SDB1/MNT/SDB1 ext3 defaults,acl 0 0
Command Setfacl set ACL
-M change
-X Delete the specified permission
-B Delete permission
-K Delete Default permissions
-D Set default permissions
--test Test mode
-R Recursive processing
[D:]u:<uid|username>: permission specifies the user's ACL
[D:]g:<gid|groupname>: Permissions specify ACLs for groups
[d:]o: Permissions specify ACLs for other people
M: Permissions Specify valid Permissions
#setfacl –m U:test:6 or Rw/common
#setfacl –m G:test:7 or Rwx/common
Command Getfacl View ACLs
#getfacl/common
6.cal Viewing calendars
which find command path
Man view Help file
PWD Displays the current directory
Stat Display file Status command
7. #logout Sign Out
#history –c Clear all the commands that were played.
#su –u2 Switch User is initialized in both BASHRC and Bash_profile
#su U2 Switch User in BASHRC initialization
#route –n View Routing table commands
#ls/lib/modules/' uname-r '/kernel/fs view supported file systems
#ps –aux All the processes that are running
#ssh User name @ host IP
#ls | Grep–v A | Xargs RM–RF Remove Reverse
#cat/etc/vsftpd/vsftpd.conf | Grep–v "#" | Grep–v "^$" does not display blank lines and lines that begin with #
8. Automatic and manual mounting
Auto mounts when auto starts or enters mount-a in the terminal
Noauto devices (partitions) can only manually mount the file system can mounted only explicitly.
9.

Some command tips