Linux System Review Memorandum 6

Linux System Review Memorandum 6 This is the sixth article in this series, mainly about periodic tasks and software configuration management. 6.1 In LINUX, a periodic process refers to a series of commands or scripts that run on a scheduled basis. In short, a periodic process is a system... information & nbsp Linux System Review Memorandum 6 This is the sixth article in this series, mainly including periodic tasks and software configuration management content. 6.1 in a LINUX system, a periodic process refers to a series of commands or scripts that run regularly. In short, it refers to the cron process in the system. This is a daemon. Generally, there are three configuration files for this process in the system:/etc/crontab,/etc/cron. d and/var/spool/cron. Generally, each user's crontab file is stored in the/var/spool/cron directory. For tasks manually maintained by the system administrator, they are placed in the/etc/crontab file. in the 6.2 crontab file format, the first column of each line can be annotated with #, meaning that there cannot be spaces at the beginning of the line. The content consists of 6-7 fields, meaning minute hour day month week [user name] command line asterisk * represents match all characters; integer represents exact match; short line can be connected to an integer, it indicates the range of values. you can also use commas to separate integers or ranges. whitelist matches the listed values. Let's take a look at several examples: 45 10 ** 1-5 CMD, which indicates that a command is executed from Monday to Friday at A.M. 0, 30*13*5 indicates the Friday half hour and the 13th half hour of each month. In CMD, it can be any valid shell command without quotation marks and can contain spaces or tabs. 6.3 The crontab command has several commands that need to be understood, including: crontab-l outputs content to the standard output, and crontab-r will delete it, crontab-e allows you to edit a new task. 6.4 software configuration is essential for system administrators to install systems and software. However, due to the relationship between LINUX systems, this work usually takes much longer than WIN systems. For the redhat system, the software package management tool is obviously rpm. of course, ubuntu uses dpkg. for this packaging tool, the common parameters are as follows: Rpm: -- install -- upgrade -- erase -- query Dpkg: -- install -- remove-l of course, the best package management tool is Apt.