1. Setting Up a Typing Break 设置在固定的时间休息。
Typing for a long period of time can be not only tiring, but it can also increase the risk of serious health problems, such as carpal tunnel syndrome. One way of preventing this is to configure the system to enforce the typing break. Simply selectSystem → Preferences → Keyboardfrom the panel, click theTyping Breaktab, and select the Lock screen to enforce typing break checkbox.
T o increase or decrease the amount of time you want to be allowed to type before the break is enforced,click the up or down button next to the Work interval lasts label respectively. You can do the same with the Break interval lasts setting to alter the length of the break itself. Finally, select the Allow postponing of breaks checkbox if you want to be able to delay the break in case you need to finish the work. T he changes take effect immediately.
Next time you reach the time limit, you will be presented with a screen advising you to take a break, and a clock displaying the remaining time. If you enabled it, the Postpone Break button will be located at the bottom right corner of the screen.
2.Change date in command line -- 设置时间
1. Change the current date. T ype the command in the following form. at a
shell prompt, replacing the
YYYY with a four-digit year, MM with a two-digit month, and DD with a two-digit day of the month:
~]# date +%D -s YYYY-MM-DD
For example, to set the date to 2 June 2010, type:
~]# date +%D -s 2010-06-02
2. Change the current time. Use the following command, where HH stands for an hour, MM is a minute,
and SS is a second, all typed in a two-digit form.:
~]# date +%T -s HH:MM:SS
If your system clock is set to use UT C (Coordinated Universal T ime), add the following option:
~]# date +%T -s HH:MM:SS -u
For instance, to set the system clock to 11:26 PM using the UT C, type:
~]# date +%T -s 23:26:00 -u
You can check your current settings by typing date without any additional argument:
Example 2.1. Displaying the current date and time
~]$ date
Wed Jun 2 11:58:48 CEST 2010
3. User Private Groups
Red Hat Enterprise
Linux uses a user private group (UPG) scheme, which makes UNIX groups easier to manage. A user private group is created whenever a new user is added to the system. It has the same name as the user for which it was created and that user is the only member of the user private group.User private groups make it safe to set default permissions for a newly created file or directory, allowing both the user and the group of that user to make modifications to the file or directory.
T he setting which determines what permissions are applied to a newly created file or directory is called aumaskand is configured in the /etc/bashrc file. T raditionally on UNIX systems, the um ask is set to 022, which allows only the user who created the file or directory to make modifications. Under this scheme, all other users, including members of the creator's group, are not allowed to make any modifications. However, under the UPG scheme, this “group protection” is not necessary since every user has their own private group.
