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Crontab usage and Cron Example

           Cron is a daemon that executes scheduled commands. Cron is started automatically from /etc/init.d on entering multi-user runlevels. Cron searches its spool area (/var/spool/cron/crontabs) for crontab files (which are named after accounts in /etc/passwd); crontabs found are loaded into memory. Note that crontabs in this directory should not be accessed directly - the crontab command should be used to access and update them.

Cron also reads /etc/crontab, which is in a slightly different format (see crontab(5)). Additionally, cron reads the files in /etc/cron.d.

Libzypp/ZYpp Programmers guide

              This is a recompilation of knowledge and common pitfalls which arose during ZYpp development.

Standard Input and Output Redirection

              The shell and many UNIX commands take their input from standard input (stdin), write output to standard output (stdout), and write error output to standard error (stderr). By default, standard input is connected to the terminal keyboard and standard output and error to the terminal screen.
 

IPC:Shared Memory

        Shared Memory is an efficeint means of passing data between programs. One program will create a memory portion which other processes (if permitted) can access.

        In the Solaris 2.x operating system, the most efficient way to implement shared memory applications is to rely on the mmap() function and on the system's native virtual memory facility. Solaris 2.x also supports System V shared memory, which is another way to let multiple processes attach a segment of physical memory to their virtual address spaces. When write access is allowed for more than one process, an outside protocol or mechanism such as a semaphore can be used to prevent inconsistencies and collisions.

Working with Wildcards

Shells support a rich set of wildcards to help work with files. Awildcard is an expression that the shell uses to expand to a number of file names&mdashthat is, to all files that match the expression. Wildcards are often called globs. The use of globs is called globbing.