This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
CIS 90 - Lesson 11
Lesson Module Status• Slides – • Properties -• Flash cards – • No-stress quiz – • Web calendar summary – • Web book pages – • Commands – • Lab – email out tech file, turn on link• Supplies ()• Email tech to class -• Class PC's – na• Scripts () – done
CIS 90 - Lesson 11
Quiz
Please close your books, turn off your monitor, take out a blank piece of paper and answer the following questions:
•What command shows the current running processes?
•Name four states a process can be in.
•What is the difference between the fork and exec system calls?
13. What complete command (with no “;”s) counts all the files belonging to you on the system, places a sorted list of them in the file allmine, and redirects error messages to the bit bucket?
find will list all files starting at / on the UNIX file tree
Limits the files listed to just those owned by the user. The shell replaces $LOGNAME with the actual username.
Permission errors are thrown away (from trying to list or traverse directories you don't have read and execute permission)
The tee send the sorted files to both the file allmine and to the stdin of the wc command
Use Opus to verify your answer
CIS 90 - Lesson 11
Test 2 Q28 answer
28. Given the file problems contains:
2+25/0
What complete command using bc would input the math problems in problems, append the calculated answers to the file answers and write any errors to the file errors?
bc < problems >> answers 2> errors
stdin redirected from keyboard to file problems
stdout redirected from terminal to append to file answers
stderr redirected from terminal to file errors
ok
mistakes
answers
errors
problems
bc
CIS 90 - Lesson 11
Test 2 Q28 verification
28. Given the file problems contains:
2+25/0
What complete command using bc would input the math problems in problems, append the calculated answers to the file answers and write any errors to the file errors?
To verify your answer on Opus, create the problems file the test your answer
CIS 90 - Lesson 11
Test 2 Q19 answer
19. Given this directory structure:
If your current working directory is dogs, what single command using filename expansion characters would move just the files Scout and Sally to the dogs directory?
mv /tmp/new/S[ca]* .
The shell replaces this with:/tmp/new/Scout and /tmp/new/Sally
here
CIS 90 - Lesson 11
Test 2 Q19 verification/home/cis90/roddyduk $ cd /tmp/tmp $ mkdir -p pets pets/dogs pets/cats new/tmp $ cd new; touch Spot Sidney Scout Sally; cd ../tmp $ ls -R pets newnew:Sally Scout Sidney Spot
Benji tries using the keyboard to send a SIGINT using Ctrl-Cbut nothing happens (because app is ignoring SIGINT)
CIS 90 - Lesson 11
SignalsBenji runs app
Benji tries using the keyboard to send a SIGQUIT using Ctrl-\but but app reacts by saying "quit it"
CIS 90 - Lesson 11
SignalsBenji runs app
Benji asks his friend Duke to kill off his stalled app process. Duke uses ps to look it up but does not have permission to kill it off
CIS 90 - Lesson 11
SignalsBenji runs app
Benji logs into another Putty session and sends a SIGINT using the kill command …. but nothing happens
CIS 90 - Lesson 11
SignalsBenji runs app
Benji ups the anty and sends two SIGQUITs but the app process shrugs them off with two "quit it!" messages
CIS 90 - Lesson 11
SignalsBenji runs app
Benji decides to send a SIGTERM this time and the app process finishes, cleans up and exits
CIS 90 - Lesson 11
SignalsBenji runs app
The same thing happens again another day. This time Benji does not care what happens with app …
CIS 90 - Lesson 11
SignalsBenji runs app
So he sends a SIGKILL this time … and app never even sees it coming …. poof … app is gone
CIS 90 - Lesson 11
LoadBalancing
CIS 90 - Lesson 11
Load Balancing
So that the multiprocessing CPU on a UNIX system does not get overloaded, some processes need to be run during low peak hours such as early in the morning or later in the day.
The at command is for this purpose.
The at command reads its stdin for a list of commands to run, and begins running them at the time of day specified as the first argument:
$ at 10:30pm < batch_file
$ at 11:59pmat> cat files.out bigshell > lab08at> cp lab08 /home/rsimms/cis90/$LOGNAME at> Ctrl-D$ Note: the Ctrl-d must be entered as the first character on the last line.
CIS 90 - Lesson 11
Load Balancing
Several ways to specify a future time to run
This job makes a backup of myscript and sends an email when finished
Use the atq command to show queued jobs
CIS 90 - Lesson 11
Load Balancing
The atrm command is used to remove jobs from the queue
The jobs command lists processes running or suspended in the background.
The atq command lists jobs queued to run in the futures that were scheduled by at command
CIS 90 - Lesson 11
SignalsClass Exercise
• View the ../depot/app program• Look for the three trap handlers
• Signal 2 (SIGINT)• Signal 3 (SIGQUIT)• Signal 15 (SIGTERM)
• Run app• Try sending it a SIGINT from the keyboard (Ctrl-C)• Try sending it a SIGQUIT from the keyboard (Ctrl-\)• Login to a second Putty session
• Use the ps –u $LOGNAME to find the app PID• Send it a SIGINT (kill -2 PID)• Send it a SIGQUIT (kill -3 PID)• Now send either a SIGKILL (9) or SIGTERM (15) but
first decide if app can clean up or not when it gets your signal.
CIS 90 - Lesson 11
vi
vi practice
CIS 90 - Lesson 11
• Bring up the vi reference page at:
http://simms-teach.com/docs/vi-ref.html
• Create a directory called practice
• Copy the following files to practice/
/home/cis90/depot/*
viMoving around in a file
CIS 90 - Lesson 11
/
h moves the cursor one character to the leftj moves the cursor down one linek moves the cursor up one linel moves the cursor one character to the rightw moves the cursor one “word” forwardb moves the cursor one “word” back0 (zero) moves the cursor to the beginning of the line$ moves the cursor to the end of the lineG moves the cursor to the last line in the file1G moves the cursor to the first line in the file105G moves the cursor to line 105^d scrolls down 10 lines^u scrolls up 10 lines^f page forward one page^b page back one page
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
Try typing a number in front of these commands and notice what happens
viPractice using these commands
CIS 90 - Lesson 11
h moves the cursor one character to the leftj moves the cursor down one linek moves the cursor up one linel moves the cursor one character to the rightw moves the cursor one “word” forwardb moves the cursor one “word” back0 (zero) moves the cursor to the beginning of the line$ moves the cursor to the end of the lineG moves the cursor to the last line in the file1G moves the cursor to the first line in the file105G moves the cursor to line 105^d scrolls down 10 lines^u scrolls up 10 lines^f page forward one page^b page back one page
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
Try typing a number in front of these commands and notice what happens
viReading and Writing out files
CIS 90 - Lesson 11
:q exits vi if you have saved your changes:q! exits vi even if you have not saved your changes:w saves any changes you've made to the file you are editing:w filename saves your file to a new name (like Save As):w! filename saves your file to a new name overwriting any previous data:r filename reads in the contents of filename starting from the cursor position:e filename replaces the current content with the content from filename
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
viNow practice these commands
CIS 90 - Lesson 11
:q exits vi if you have saved your changes:q! exits vi even if you have not saved your changes:w saves any changes you've made to the file you are editing:w filename saves your file to a new name (like Save As):w! filename saves your file to a new name overwriting any previous data:r filename reads in the contents of filename starting from the cursor position:e filename replaces the current content with the content from filename
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
viEntering Input mode
CIS 90 - Lesson 11
/
i Ready to insert characters immediately before the current cursor positiona Ready to append characters immediately after the current cursor positionI Ready to insert characters at the start of the current lineA Ready to append characters at the end of the current lineo Ready to input characters in a new line that opens up below the cursorO Ready to input characters in a new line that opens up above the cursorr Ready to replace the current character with the character you type nextR Ready to Replace (overwrite) characters starting at the curent cursor positions Ready to replace the current character with the string you type nextcw Ready to replace the current word with the string you type next
viNow practice these commands
CIS 90 - Lesson 11
/
i Ready to insert characters immediately before the current cursor positiona Ready to append characters immediately after the current cursor positionI Ready to insert characters at the start of the current lineA Ready to append characters at the end of the current lineo Ready to input characters in a new line that opens up below the cursorO Ready to input characters in a new line that opens up above the cursorr Ready to replace the current character with the character you type nextR Ready to Replace (overwrite) characters starting at the curent cursor positions Ready to replace the current character with the string you type nextcw Ready to replace the current word with the string you type next
viCut, Copy, Pasting Commands
CIS 90 - Lesson 11
x Deletes the current characterdw Deletes the current worddd Deletes the current lineD Deletes to the end of the lineyy Copies a line to the clipboard bufferp Pastes whatever is in the clipboard buffer below the current cursorP Pastes whatever is in the clipboard buffer above the current cursor
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
viNow practice these commands
CIS 90 - Lesson 11
x Deletes the current characterdw Deletes the current worddd Deletes the current lineD Deletes to the end of the lineyy Copies a line to the clipboard bufferp Pastes whatever is in the clipboard buffer below the current cursorP Pastes whatever is in the clipboard buffer above the current cursor
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
viMiscellaneous Useful Commands
CIS 90 - Lesson 11
^g Tells you the filename you are editing and what line your cursor is onu Undoes the last command you executed. Repeats the last command you executed/string Searches for the string of characters in the filen Finds the next occurrence of the current search string looking down the fileN Finds the next occurrence of the current search string looking up the file~ Changes the case of the current character
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
viNow practice these commands
CIS 90 - Lesson 11
^g Tells you the filename you are editing and what line your cursor is onu Undoes the last command you executed. Repeats the last command you executed/string Searches for the string of characters in the filen Finds the next occurrence of the current search string looking down the fileN Finds the next occurrence of the current search string looking up the file~ Changes the case of the current character
Note: to execute any of the following commands from vi, you must be in command mode. Press the Esc key to enter command mode.
CIS 90 - Lesson 11
http://vim.wikia.com/wiki/Main_Page
CIS 90 - Lesson 11
The Mug of vi
CIS 90 - Lesson 11
/home/cis90/simmsben $ mail roddydukSubject: Good bonesHey Duke,I really appreciate thatbone you sent me last week.Let me knwo if you want to go mark some fench poststhis weekend.Later,Ben
/bin/mail and vi
You are composing a message and you spot some typos … CRUD … what can you do?
CIS 90 - Lesson 11
/home/cis90/simmsben $ mail roddydukSubject: Good bonesHey Duke,I really appreciate thatbone you sent me last week.Let me knwo if you want to go mark some fench poststhis weekend.Later,Ben~v
/bin/mail and vi
Well … you could try the ~v command
CIS 90 - Lesson 11
/bin/mail and vi
The message is loaded into vi where changes or additions can be made. :wq is used to save and quit vi
CIS 90 - Lesson 11
/bin/mail and vi
The earlier text with typos is still showing, however the corrected version is what is actually sent.
/home/cis90/simmsben $ mail roddydukSubject: Good bonesHey Duke,I really appreciate thatbone you sent me last week.Let me knwo if you want to go mark some fench poststhis weekend.Later,Ben~v(continue).Cc:/home/cis90/simmsben $
/home/cis90/roddyduk $ mailMail version 8.1 6/6/93. Type ? for help."/var/spool/mail/roddyduk": 1 message 1 unread>U 1 [email protected] Mon Nov 10 20:25 22/782 "Good bones"& 1Message 1:From [email protected] Mon Nov 10 20:25:32 2008Date: Mon, 10 Nov 2008 20:25:32 -0800From: Benji Simms <[email protected]>To: [email protected]: Good bones
Hey Duke,I really appreciate that bone you sent me last week.Let me know if you want to go mark some fence poststhis weekend.Later,Ben
&
CIS 90 - Lesson 11
/bin/mail and vi
The message Duke reads has all the typos fixed.
CIS 90 - Lesson 11
Spelland Lab 9
CIS 90 - Lesson 11
spell command
spell command flags CIS as misspelled word.
How can we add CIS to the dictionary?
Hmmm. No man page for spell ????????????
OK, the actual command is aspell
CIS 90 - Lesson 11
spell command
spell command flags CIS as misspelled word. How can we add CIS to the dictionary?
DESCRIPTION aspell is a utility that can function as an ispell -a replacement, as an independent spell checker, as a test utility to test out Aspell features, and as a utility for managing dictionaries.
COMMANDS <command> is one of:
-?,help display the help message
-c,check file to spell-check a file
CIS 90 - Lesson 11
spell command
There must be a way to add CIS …. but … lets try google
CIS 90 - Lesson 11
spell command
googling "linux aspell personal dictionary" yields this page
Bingo! Thank you Samat Jain
CIS 90 - Lesson 11
spell command
It works!!
CIS 90 - Lesson 11
FinalProject
/home/cis90/roddyduk $ cat ../depot/dialog#!/bin/bashecho -n "Which user? "read USERecho -n "Starting in what directory? "read DIRNUM=$(find $DIR -user $USER 2> /dev/null | tee files.$USER | wc -l)echo "BTW, that is $NUM files I found for you"echo "The names are in files.$USER"echo -n "Press Enter to see them now "read ANSWERcat files.$USERexit/home/cis90/roddyduk $
CIS 90 - Lesson 11
Custom front-end to a command
CIS 90 - Lesson 11
Wrap up
CIS 191 - Lesson 11
New commands:vi Run vi editor
New Files and Directories:xx xxxxx
CIS 90 - Lesson 11
Next Class
Assignment: Check Calendar Page on web site to see what is due next week.
Quiz questions for next class:
• How do you send a SIGKILL to one of your own processes?
• What vi command is used to exit vi without saving any of the changes you made?