OSN ASSIGNMENT 3 (Extension of 2nd Assignment)

NAME       Vempati Siva Koti Reddy

ROLLNO   2021101135

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REQUIREMENTS:

• GCC compiler
• LINUX OS (Ubuntu)

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• To execute the program:

$ make
$ ./a.out

Specification 1 :

• Doing input output redirections using the symbols <, > and >>;
• Creating the output file (with permissions 0644) if it does not exist.
• Didn't handle multiple inputs and outputs as those are not required.
• Used execvp.
• Handling errors if file doesn't exist.

Specification 2 :

• Implemented piping using dup2
• Handled Errors
• One or more commands can be piped

Specification 3 :

• Implemented IO Redirection with command pipelines

• Getting output for io redirection within command lines

• First 3 specifications implemented in ioredirection.c

Specification 4 :

• (i) jobs :

• Printing jobs running & stopped with specified flags

• Didn't sort jobs in Alphabetical Order

• Printing with status and pid

• Doing further fg, bg and sig operations with assigned job numbers as mentioned

• (ii) sig :

• Passing job number of a running job and a corresponding signal number to do sig operation with kill.

• Handling all errors

• (iii) fg :

• Converting a job which is running in background to foreground

• Changing background running or stopped processes to foreground running processes

• Foreground processes obtained with fg conversion : Stored in seperate

• Handled all type of errors

• (iv) bg :

• Changing a stopped background process to running background process

• All errors handled like giving error if job with given number is not available, and intimating if the chosen process is already running in background.

• Implemented these parts in jobs.c

Specification 5 :

• As mentioned in pdf, Handling signals with Ctrl-Z, Ctrl-C and Ctrl-D

• Ctrl - Z pushes currently running foreground job into background.

• Changing its state from running to stopped

• Ctrl - C to interrupt currently running foreground process

• No effects if no foreground running process

• Ctrl - C, Ctrl - Z makes Ctrl -D work to log out from shell

• Implemented this part in signals.c

Specification 6 :

• Auto completing using stat, searching files starting with same characters using strncmp

• Used main.c provided in mail

• Handled all type of errors

• Implemented in scan.c

Thank You :)