Operating Systems 2017F Lecture 8 - Revision history

Akhil at 01:21, 9 October 2017

2017-10-09T01:21:10Z

← Older revision		Revision as of 01:21, 9 October 2017
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	Commands:		Commands:

	lspci: shows you which hardware you are working with		lspci: shows you which hardware you are working with

Akhil at 01:16, 9 October 2017

2017-10-09T01:16:12Z

← Older revision		Revision as of 01:16, 9 October 2017
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	This class was review of older classes and answering questions (No new topics)		This class was review of older classes and answering questions (No new topics)

	~~User mode: only mode available to us~~
	~~Kernel: make a request for memory~~
	~~Kernel: abstracts that, it provides you with the RAM you need to access by providing an address~~
	~~What is a process: a running program~~

	~~What is a program~~: ~~set of the instructions, given~~ to ~~the CPU to execute line by line~~		User mode: only mode available to us as users.

	Command line/~~sell~~/terminal: ~~all same thing~~		Kernel: Abstracts hardware so we can use it. eg. we request memory, kernel handles the actual allocation, etc.


			What is a process: a running program, set of the instructions, given to the CPU to execute line by line

			Command line/shell/terminal: This is how we can interact with the OS without a desktop environment.

	How do processes communicate with each other ?		How do processes communicate with each other ?
	They send signals to each other. ~~For example,~~ parent ~~knows that child has executed~~ when it ~~receives signal~~		They send signals to each other. eg. Child sends a signal to parent when it has finished execution.

	PS: ~~list of~~ process		Orphan process: parent has finished executing and terminated, leaving an "orphaned" child process who's parent process will now be a process from a higher level (grandfather process).

	~~Orphan~~ process: ~~parent~~ has finished executing ~~and terminated leaving an "orphaned" child~~ process ~~who~~ parent ~~process will become a process from a higher level~~		Zombie process: Process that has finished executing but its entry still exists in the process list. In this case, the parent is still up and running.

	~~Zombie process: Process that has finished executing but its entry still exists in the process list (parent does not wait for child to terminate before it dies)~~

	File system: managing the hard drive, ~~writing~~ and reading to a file etc.		File system: managing/organizing the hard drive, control how data is stored/retrieved. Writing and reading from/to a file etc. examples of special files like /proc, etc.

	~~Environment: where we are working~~		inode is a data structure in linux that is used to store file metadata information like size of file, timestamps, type of file, etc. (however, it does NOT store the name or actual data of the file).

	~~Environment variable: is where configurations are stores, all start with “$” signs. To check resolutions etc. find any info like user etc.~~

	~~Configurations~~ are ~~stored in an environment variable like $USER~~		Environment: where we are working.

	~~$PATH stores list~~ of ~~all folders that tells shells where to look for~~		Environment variable: is where configurations/information about the system/current environment are stored. eg. username, type of terminal being used, prompt, etc.

	~~envp[] stores all~~ environment ~~variables~~		"echo $USER" in terminal to check the value of "user" environment variable.

	~~Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).~~

	~~File system Device files stored in /dev~~		Difference between static and dynamic compilation:

	~~Path~~: ~~List of all folder into which the shell looks at to find a program if not giving~~ it ~~a full path . “looking for the path to find a program we want to run”~~.		Dynamically linked file: loads code from libraries as it needed.
	~~Memory is not continuous~~
	~~Everything is linux is a file ,~~
	~~Difference between static and dynamic compilation:~~

	~~Dynamically linked file: loads code as it needs it~~		Libraries are dynamically loaded into memory versus when they are loaded statically.

	~~Libraries are dynamically loaded~~ into ~~memory versus when they~~ are ~~loaded statically~~		Statically linked file: loads relevant code into the binary during compilation so no library calls are made during runtime. This is why ltrace gives error.

	~~Man pages are helpful…~~

	Commands:		Commands:
	~~LSPCI~~: shows you which hardware you are working with		lspci: shows you which hardware you are working with
	~~Ps : to find a process ID , coming from the kernel~~
	~~Ps – aux~~
	~~Pstree: displayes the family tree . systemd : first one , always wait on the child and checks if the child has to report something to prevent zombie processes.~~
	~~SIGCHILD : how processes communicate , they send signals to communicate with each other and SIGCHILD is one of them~~
	~~A child send it to the parent when it is done its task.~~

	~~X clock & : generates a clock ?~~
	~~How to redirect a file into a text file?~~

	ps ~~aux \| grep xclock > ps.log~~		ps : to find a process ID , coming from the kernel

	~~Generate~~ a ~~file on a strace on a program: we should know~~ the ~~command line to do this~~		ps – aux

	~~Echo $USER : to identify user name~~		pstree: displayes the family tree
	~~Envp[]~~ : ~~stores all~~ the ~~env variables you have~~
	~~/proc/ 1237 ls~~		systemd : first one , always wait on the child and checks if the child has to report something to prevent zombie processes.
	~~/proc/1237$~~
	~~Man man~~		Man pages are helpful…
	~~Man readlink~~ : ~~shell command~~ , ~~also a system call~~		"Man man" for more information
	~~Xclock ; is~~ the child of the ~~bash terminal~~
	~~(Do a while loop or a for loop to parse it )~~
	~~^ /proc/2363 status? The you get the RAM and all info about the process~~

Rquaium at 03:57, 5 October 2017

2017-10-05T03:57:05Z

← Older revision		Revision as of 03:57, 5 October 2017
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			== Notes ==
	This class was review of older classes and answering questions (No new topics)		This class was review of older classes and answering questions (No new topics)

Rquaium at 03:43, 5 October 2017

2017-10-05T03:43:02Z

← Older revision		Revision as of 03:43, 5 October 2017
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	$PATH stores list of all folders that tells shells where to look for		$PATH stores list of all folders that tells shells where to look for

	*envp[] stores all environment variables		envp[] stores all environment variables

	Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).		Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).

Rquaium: Added notes for Tuesday's (October 3d) lecture

2017-10-05T03:42:37Z

Added notes for Tuesday's (October 3d) lecture

← Older revision		Revision as of 03:42, 5 October 2017
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	Path: List of all folder into which the shell looks at to find a program if not giving it a full path . “looking for the path to find a program we want to run”.		Path: List of all folder into which the shell looks at to find a program if not giving it a full path . “looking for the path to find a program we want to run”.
	*memory is not continuous		Memory is not continuous
	*everything is linux is a file ,		Everything is linux is a file ,
	Difference between static and dynamic compilation:		Difference between static and dynamic compilation:

Line 59:		Line 59:
	ps aux \| grep xclock > ps.log		ps aux \| grep xclock > ps.log

	*Generate a file on a strace on a program: we should know the command line to do this		Generate a file on a strace on a program: we should know the command line to do this

	Echo $USER : to identify user name		Echo $USER : to identify user name

Rquaium at 03:41, 5 October 2017

2017-10-05T03:41:29Z

← Older revision		Revision as of 03:41, 5 October 2017
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	Orphan process: parent has finished executing and terminated leaving an "orphaned" child process who parent process will become a process from a higher level		Orphan process: parent has finished executing and terminated leaving an "orphaned" child process who parent process will become a process from a higher level

	Zombie process: Process that has finished executing but its entry still exists in the process list (parent does not wait for child to terminate before it dies)		Zombie process: Process that has finished executing but its entry still exists in the process list (parent does not wait for child to terminate before it dies)

	~~Tutorial 2 question : what happens if you removed that line? The program will get stuck and the parent will be waiting if the child is finished. NOT FINISHED THE CHECKING.~~
	*we don’t necessarily need a system environment

	File system: managing the hard drive, writing and reading to a file etc.		File system: managing the hard drive, writing and reading to a file etc.

Rquaium at 03:40, 5 October 2017

2017-10-05T03:40:50Z

← Older revision		Revision as of 03:40, 5 October 2017
Line 39:		Line 39:

	Path: List of all folder into which the shell looks at to find a program if not giving it a full path . “looking for the path to find a program we want to run”.		Path: List of all folder into which the shell looks at to find a program if not giving it a full path . “looking for the path to find a program we want to run”.
	*memory is not continuous		*memory is not continuous
	*everything is linux is a file ,		*everything is linux is a file ,
	Difference between static and dynamic compilation:		Difference between static and dynamic compilation:
Line 59:		Line 59:
	X clock & : generates a clock ?		X clock & : generates a clock ?
	How to redirect a file into a text file?		How to redirect a file into a text file?
	ps aux \| grep xclock > ps.log
			ps aux \| grep xclock > ps.log

	*Generate a file on a strace on a program: we should know the command line to do this		*Generate a file on a strace on a program: we should know the command line to do this

Rquaium at 03:40, 5 October 2017

2017-10-05T03:40:27Z

← Older revision		Revision as of 03:40, 5 October 2017
Line 1:		Line 1:
	This class was review of older classes and answering questions (No new topics)		This class was review of older classes and answering questions (No new topics)

	User mode: only mode available to us		User mode: only mode available to us
	Kernel: make a request for memory		Kernel: make a request for memory

Rquaium at 03:39, 5 October 2017

2017-10-05T03:39:35Z

← Older revision		Revision as of 03:39, 5 October 2017
Line 4:		Line 4:
	Kernel: abstracts that, it provides you with the RAM you need to access by providing an address		Kernel: abstracts that, it provides you with the RAM you need to access by providing an address
	What is a process: a running program		What is a process: a running program

	What is a program: set of the instructions, given to the CPU to execute line by line		What is a program: set of the instructions, given to the CPU to execute line by line

	Command line/sell/terminal: all same thing		Command line/sell/terminal: all same thing

	How do processes communicate with each other ?		How do processes communicate with each other ?
	They send signals to each other. For example, parent knows that child has executed when it receives signal		They send signals to each other. For example, parent knows that child has executed when it receives signal
Line 17:		Line 20:
	Tutorial 2 question : what happens if you removed that line? The program will get stuck and the parent will be waiting if the child is finished. NOT FINISHED THE CHECKING.		Tutorial 2 question : what happens if you removed that line? The program will get stuck and the parent will be waiting if the child is finished. NOT FINISHED THE CHECKING.
	*we don’t necessarily need a system environment		*we don’t necessarily need a system environment
	File system: managing the hard drive, writing and reading to a file etc.
			File system: managing the hard drive, writing and reading to a file etc.

	Environment: where we are working		Environment: where we are working

	Environment variable: is where configurations are stores, all start with “$” signs. To check resolutions etc. find any info like user etc.		Environment variable: is where configurations are stores, all start with “$” signs. To check resolutions etc. find any info like user etc.

	Configurations are stored in an environment variable like $USER		Configurations are stored in an environment variable like $USER

	$PATH stores list of all folders that tells shells where to look for		$PATH stores list of all folders that tells shells where to look for

Line 26:		Line 34:

	Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).		Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).




	File system Device files stored in /dev		File system Device files stored in /dev
Line 61:		Line 66:
	/proc/ 1237 ls		/proc/ 1237 ls
	/proc/1237$		/proc/1237$
	~~Send them to raiyan Quaium with a “.”~~
	Man man		Man man
	Man readlink : shell command , also a system call		Man readlink : shell command , also a system call
Line 68:		Line 72:
	^ /proc/2363 status? The you get the RAM and all info about the process		^ /proc/2363 status? The you get the RAM and all info about the process

	~~Tutorials:~~
	~~Tutorial 1; library calls (not necessary in C code)provided by the operating system or by the C library~~
	~~Printf : system call , apart of the C library~~
	~~Difference between Dynamically and statically compilation?~~
	Answer : static don’t make library calls since they already include them, dynamic compilation loads the library into memory then it is refrences. In run time: it has to read an access library then it doesn’t write. <- this is dynamic (Assignment question, dynamic is more efficient according to Google) since the library does not need to be loaded multiple times.
	~~Ld : dynamic library~~
	~~Dynamically linked files:~~
	~~Tutorial 2, doing it:~~
	~~To run in the background ls &~~
	~~Bc, 1+1 ; don’t have access to my shell unless I exit this~~
	~~Bc & but its very laggy and you cant quit~~
	~~3) Ps aux \| grep mc~~
	~~4) zombie process~~

Rquaium: Created page with "This class was review of older classes and answering questions (No new topics) User mode: only mode available to us Kernel: make a request for memory Kernel: abstracts that,..."

2017-10-05T03:37:50Z

Created page with "This class was review of older classes and answering questions (No new topics) User mode: only mode available to us Kernel: make a request for memory Kernel: abstracts that,..."

New page

This class was review of older classes and answering questions (No new topics)
User mode: only mode available to us
Kernel: make a request for memory
Kernel: abstracts that, it provides you with the RAM you need to access by providing an address
What is a process: a running program
What is a program: set of the instructions, given to the CPU to execute line by line
Command line/sell/terminal: all same thing
How do processes communicate with each other ?
They send signals to each other. For example, parent knows that child has executed when it receives signal

PS: list of process

Orphan process: parent has finished executing and terminated leaving an "orphaned" child process who parent process will become a process from a higher level

Zombie process: Process that has finished executing but its entry still exists in the process list (parent does not wait for child to terminate before it dies)

Tutorial 2 question : what happens if you removed that line? The program will get stuck and the parent will be waiting if the child is finished. NOT FINISHED THE CHECKING.
*we don’t necessarily need a system environment
File system: managing the hard drive, writing and reading to a file etc.
Environment: where we are working
Environment variable: is where configurations are stores, all start with “$” signs. To check resolutions etc. find any info like user etc.
Configurations are stored in an environment variable like $USER
$PATH stores list of all folders that tells shells where to look for

*envp[] stores all environment variables

Data structure stores data. Inode is a datastructure on a filesystem in linux that is used to store file information (however, it does NOT store the name or actual data of the file).

File system Device files stored in /dev

Path: List of all folder into which the shell looks at to find a program if not giving it a full path . “looking for the path to find a program we want to run”.
*memory is not continuous
*everything is linux is a file ,
Difference between static and dynamic compilation:

Dynamically linked file: loads code as it needs it

Libraries are dynamically loaded into memory versus when they are loaded statically

Man pages are helpful…

Commands:
LSPCI: shows you which hardware you are working with
Ps : to find a process ID , coming from the kernel
Ps – aux
Pstree: displayes the family tree . systemd : first one , always wait on the child and checks if the child has to report something to prevent zombie processes.
SIGCHILD : how processes communicate , they send signals to communicate with each other and SIGCHILD is one of them
A child send it to the parent when it is done its task.

X clock & : generates a clock ?
How to redirect a file into a text file?
ps aux | grep xclock > ps.log

*Generate a file on a strace on a program: we should know the command line to do this

Echo $USER : to identify user name
Envp[] : stores all the env variables you have
/proc/ 1237 ls
/proc/1237$
Send them to raiyan Quaium with a “.”
Man man
Man readlink : shell command , also a system call
Xclock ; is the child of the bash terminal
(Do a while loop or a for loop to parse it )
^ /proc/2363 status? The you get the RAM and all info about the process

Tutorials:
Tutorial 1; library calls (not necessary in C code)provided by the operating system or by the C library
Printf : system call , apart of the C library
Difference between Dynamically and statically compilation?
Answer : static don’t make library calls since they already include them, dynamic compilation loads the library into memory then it is refrences. In run time: it has to read an access library then it doesn’t write. <- this is dynamic (Assignment question, dynamic is more efficient according to Google) since the library does not need to be loaded multiple times.
Ld : dynamic library
Dynamically linked files:
Tutorial 2, doing it:
To run in the background ls &
Bc, 1+1 ; don’t have access to my shell unless I exit this
Bc & but its very laggy and you cant quit
3) Ps aux | grep mc
4) zombie process