Parcial_2_antonio_B

Criteria to organize files · quick-access necessary when a single record is accessed. -not needed if a file will be processed in batches. Easy to update-a file on CD-ROM updates and never ease storage is not considered economic. -minimum data redundancy. -redundancy can be used to speed up access. · a single-index · Maintenance cheaper. -fewer errors.· Reliability A directory can have subdirectories, thus forming a hierarchical structure in the shape of an inverted tree, is symbolized by a bar of division (/) Some directories on Linux: • / bin Contains executable programs that are part of the Linux operating system . Many Linux commands like cat, cp, ls, more and tar are located in this directory. • / bootIt contains the kernel (or kernel) of Linux and other files needed for the LILO boot manager, which performs initial loading of the operating system when the computer turns on. • / dev files contain all access devices. Linux treats each device (terminals, disks, printers, etc.). Like a special file.• / etc. Contains configuration files and software system initialization. • / home Contains user home directories. The HOME directory the directory where a user is positioned to enter the system, so it is also known as login directory or connection.• / lib contains the library files used by applications and system utilities, as well as libraries belonging to different programming languages.



protection measures are based on each file has an owner (usually the one who created the file.) Users belong to one or more groups, which are assigned by the Administrator depending on the task performed by each user. In each category of permissions (user, group and others) there are three types of access: read (Read), writing (Write) and execution (eXecute). permissions of a file or directory can be changed from KFM File Manager by using the Properties window or by using the chmod command.
System calls for process management.
pid = fork () - creates a child process identical to the parent.
pid = waitpid - wait for a child determined to end and takes out his condition.
s = wait - wait until a child process to end and takes out his condition, it returns the pid of termina.Llamada old son.
s = execve - replaces the image in memory of a process.
exit - terminates the process execution and returns the output condition.
size = brk - sets the size of the data segment (addr)
pid = getpid () - returns the id of the applicant process.
pid = getpgrp - returns the process group id of the applicant process.
pid = setsid () - creates a new session and assigns the identifier pid of the caller and process group.
s = ptrace - monitors a process to debug.