Talk:COMP 3000 2012 Midterm Material - Revision history

Sdp: added yu-gi-oh reference

2012-10-26T01:54:56Z

added yu-gi-oh reference

2012-10-26T01:30:27Z

ls -l

@@ Line 27: / Line 27: @@
      U  G  O
    -rwxrwxrwx
    Memnonic: 'You go hugo!'

2012-10-26T00:32:46Z

Other

← Older revision		Revision as of 00:32, 26 October 2012
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	Important kill signals:		Important kill signals:
	-SIGINT or -2 -> (crtl-C) sends a kill signal to program, can be ignored.		-SIGINT or -2 -> (crtl-C) sends a kill signal to program, can be ignored. SIGINT is also the default signal used by kill. (ie. kill <PID> = kill -2 <PID>)
	-SIGSTP -> (crtl-Z) sends suspend program signal, to resume it use fg <pid or jobnumber> or bg <pid or jobnumber> or send SIGCONT		-SIGSTP -> (crtl-Z) sends suspend program signal, to resume it use fg <pid or jobnumber> or bg <pid or jobnumber> or send SIGCONT
	-SIGSTOP -> same as SIGSTP, except no shortcut keys and it is unblockable.		-SIGSTOP -> same as SIGSTP, except no shortcut keys and it is unblockable.

2012-10-26T00:10:24Z

Other

← Older revision		Revision as of 00:10, 26 October 2012
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	=== Other ===		=== Other ===

	kill sends signals		kill sends signals.

			used as follows:
			"kill <-command> <PID of program>"

			Important kill signals:
			-SIGINT or -2 -> (crtl-C) sends a kill signal to program, can be ignored.
			-SIGSTP -> (crtl-Z) sends suspend program signal, to resume it use fg <pid or jobnumber> or bg <pid or jobnumber> or send SIGCONT
			-SIGSTOP -> same as SIGSTP, except no shortcut keys and it is unblockable.
			-SIGCONT -> Continue signal, resumes a stopped program
			-SIGFPE -> floating point exception (dividing by zero)
			-SIGEGV -> Segmentation fault signal.
			-SIGCHLD -> Signal sent to parent when child terminates.
			-SIGKILL or -9 -> Unblockable kill signal

2012-10-25T04:31:25Z

lab 3

← Older revision		Revision as of 04:31, 25 October 2012
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	daemon that handles syslog protocol		daemon that handles syslog protocol
	handles generic logging for system		handles generic logging for system


			== Lab 3 ==

			=== Tracing ===

			ltrace, strace
			Statically linking will make ltrace output nothing.

			=== writing to files ===

			File * f = fopen(path, "w")
			fprintf(f,"blah")
			fclose(f)

			=== exec* ===

			the exec family of functions replace the current process image with that of
			another file/binary.
			Does not return value if successful, -1 on failure
			Process keeps same PID

			execvp() inherits the current process's environment variables
			execve() needs to have the environment variables passed in as an array of pointers
			to null terminated strings.


			=== Other ===

			kill sends signals

2012-10-24T19:19:18Z

Processes

2012-10-24T19:18:45Z

= Upstart: blarg!

← Older revision		Revision as of 19:18, 24 October 2012
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	gnome. That's why we had to log into a virtual console		gnome. That's why we had to log into a virtual console

	=== Upstart ==		=== Upstart ===

	init is upstart		init is upstart

2012-10-24T19:18:20Z

added lab2

← Older revision		Revision as of 19:18, 24 October 2012
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	environment is more global, but typically a COPY is passed on to child processes		environment is more global, but typically a COPY is passed on to child processes
	envp is a series of keyvalue strings passed in with exec*		envp is a series of keyvalue strings passed in with exec*

			== Lab2 ==

			=== Processes ===

			ps aux
			ps -e
			top


			=== Processes ===

			run pstree.
			notice that cron, upstart-socket, and others are owned by init. These are daemons.

			notice that gnome display manager is a child of lightdm. Killing lightdm kills
			gnome. That's why we had to log into a virtual console

			=== Upstart ==

			init is upstart
			started by kernel. It's the only think the kernel runs in userspace

			shutdown -r now
			switches to run level 6

			shutdown -h now
			switches to run level zero

			symlinks in /etc/init.d point to /lib/init/upstart-job
			successful sysV to upstart transition

			Upstart's entire deal is revamp the ol' sysV boot seq

			traditional init process is strictly synchronous, blocking future tasks until the
			current one has completed.

			upstart is async. and allows more parralleissimsimsmmmsm

			=== Logs ===

			/var/log

			use lsof to check who's accessing a file.

			Rule of thumb.
			if logfile is generic, then written to by rsyslog (udev, auth, etc)
			if logfile has program name, written to by that program (apache)

			rsyslog
			daemon that handles syslog protocol
			handles generic logging for system

2012-10-24T18:46:58Z

Discussion =: typo

2012-10-24T18:44:49Z

← Older revision		Revision as of 18:44, 24 October 2012
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			= Discussion ==

	= ~~Christian's Concise Notes~~ =
			= Only the facts =
	I'll be putting up my notes of notes up here. Hopefully people can benefit from these. I'll be summing up the answers from the lab and adding a few more details here and there.		I'll be putting up my notes of notes up here. Hopefully people can benefit from these. I'll be summing up the answers from the lab and adding a few more details here and there.