Introduction to Operating Systems

CSCI 4061   -   Spring 2013

Examples

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Shell Scripts

hello (tcsh) - hello (bash) -  A simple Hello World shell script. name (tcsh)  -  name (tcsh) - Shell script using variables. arg_demo (tcsh)  -  arg_demo (bash)  -Shell script involving command line arguments. shift_demo (tcsh) - shift_demo (bash) - Shell script using shift with command line arguments. keyin_demo (tcsh) - keyin_demo (bash) -Shell script reading user data input from standard input. quotes_demo (tcsh) - quotes_demo (bash) - Shell script demonstrating use of quotes. forEach (tcsh) -  forEach (bash) -   example of iteration using foreach construct files_demo (tcsh) - files_demo (bash) -  Shell script dealing with files and using if-then-else. file-list-iterator  this example shows how to assign output of a system command to a shell variable filesize  (tcsh) -  filesize (bash)  - compute the sum of all files in a directory (non-recursive) numeric_demo - Shell script demonstrating numeric data processing. menu (tcsh) - menu (bash) -Demonstrating printf menu2, menu.txt - Demonstrating cat in a script ( and supporting textfile) here - Demonstrating the "here document" switch_demo (tcsh) - switch_demo (bash) -Demonstrating the use of switch switch-demo-2   Demostrating pattern matching in selecting cases in a switch statement usage - Checking & using arguments pattern2 - Avoiding quoting pitfalls main, subroutine - Using another script as a subroutine recursive, dorecursive - requires setting of environment variable, dorecursivepath requires setting of the path - Recursive usage of scripts

File I/O Examples

Echo It reads lines from stdin and writes to stdout. File copy It creates a copy of an existing file. File append It appends a file at the end of another file. seekout - an example of lseek An example of lseek, creates null bytes by seeeking beyond the end of the file. myls0.c myls1.c myls2.c myls3.c myls4.c myls5.c mylsFinal.c Example of opendir and readdir to list a directory's content. stat call, ctime, getpwuid, getgrgid statdemo.c Getting sum of all files in a directory using stat. lstatdemo.c Prints file type (dir, reg, lnk) for each file in a directory dupdemo.c Using dup to redirect output from a file to standard output. makdir.c Make a new directory rmvdir.c Remove a directory rmvfile.c Remove a file changedir.c  Change the current working directory of the process executing this code pwdir.c   getcwd.c Print current working directory myfind.c  A simple version of "find" program to find in a specified directory all files whose names contain a given string. NOTE: No wildcards accepted. If you execute as "myfind   dirname  hel" It will find files with names such as hello.c, help.txt, shell.txt,  if present in the directory tree specified by "dirname". Their names contain string "hel". linkinfo.c  This program reads all entries in a given directory, and for each  symbolic link in the directory, it prints the link information, i.e. the path information contained in the link.  This program makes use of the system call function readlink(). makelink.c  This program creates a new symbolic link (path name) for an existing file. It uses system call function symlink(). This program is similar to "ln -s" for creating a symbolic link. fmtout.c Examples for formatted output fmtinput.c Examples for formatted input. citylist Examples of input for the formatted input example program. timeinfo.c  This example shows how to use strftime(0 function to generate current date time in a desired format such as MONTH-DD-YYYY-HH-MM-SS, e.g.  Feb-13-2013-16-59-08

Process Management

Description of various examples in this section printpid.c Print process id, parent process id, user id. process-chain.c Example of repeated fork calls to create a chain of parent-child. Example 2.5 from the book. process-fan.c Example 2.6 from the book. process-tree.c Example 2.7 from the book. Example 1 Example of fork-exec using execl. Example 2 Example of fork-exec using execv. Example 3 Example of fork-exec in which the child executes a shell command Example 4 Example of fork-exec -  parent waits for child finish and return its PID as status Example 5 Parent opens the file with name "input",                      creates a child, across the fork child and parent will share the file descriptor                     both child and parent read from the same descriptor and the output  gets interleaved by the outputs of the two Example 6  Parent creates the child  and uses the WNOHANG option of waitpid. Parent is not blocked in wait. Pipeline Example of creating a pipe between two processes. Exit status of a child process Example of how a process obtains exit status of its child.

Examples of POSIX Thread Programming

POSIX Thread Programming Examples

Concurrent Programming

Serilized writing to stderr by concurrent children This example illustrates the output produced when child processes in a process chain write to stderr in a serial order. Interleaved writing to stderr by concurrent children when the writes are not synchronized. This example illustrates the output produced when child processes in a process chain write concurrently to stderr in a unsychronized manner. Examples of concurrent programming using POSIX seamphores, shared memory, System V semaphores

Examples of SYSTEM V Semaphores

System V sempahore Examples

Signal Management

Example programs for signal handling More example programs for signal handling

String Manipulation

pathparse.c Parsing a path into filename & base str_demo.c Another string manipulation demo strtok_ex.c Parsing strings into tokens using strtok get_strings.c Using fgets to retrieve strings from a file

Dynamic Memory

Shared Memory dynamic1.c A demo of malloc and free dynamic2.c A demo of calloc and realloc

TCP/IP Example Programs

TCP, UDP, sockets and select() Examples from recitation

TCP/IP Example Programs

TCP and UDP examples