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OS Services: OS provides environment for execution of programs and…
OS Services
: OS provides environment for execution of programs and services to programs and users
FILE SYSTEM MANIPULATION
create+delete
search
programs need read + write files + directories
list file info
controls permission given certain programs/users access files
permission mgt
control how files manipulated/managed
I/O
important
between user + programs
OS controls usage of I/O devices
user can't datically control input/output devices
file or I/O devices
PROGRAM EXECUTION
end execution (normally/abnormally)
run program
load program into memory
should able
USER INTERFACE
forms
Command Line Interface (CLI)
Graphical User Interface (GUI)
common
user friendly
Batch
allows user interact w/ OS or computer
important
ACCOUNTING
accumulate usage statistics
keep track which users use how much and what kinds of comp resources
RESOURCE ALLOCATION
type resources
main memory
file storage
CPU cycles
I/O devices
multiple processes/users
ERROR DETECTION
important
where
I/O devices
CPU and memory hardware
user program
for each type error, OS should take approp action to
ensure correct and consistent computing
X break down
X seize computing completely
example
printer out paper
debugging facilities greatly enhance user's and programmer's abilities to efficiently use system
COMMUNICATIONS
may be shared
via memory
through message passing
processes may exchange info, on same comp or between comps over network
PROTECTION AND SECURITY
security: prevent outside access. system X accessed outsiders. Defend input/output devices. Prevent invalid access attempts. OS record if so.
require user auth
defend external I/O devices from invalid access attempts
protection: ensure all access to system resources controlled
implement throughout system: chain only as strong as weakest link
processes
excecuting, 1 process cant interfere with others or OS itself
owners of info stored in multiuser or networked comp system may want control use of that info, concurrent processes shouldn't interfere w/ each other