Common SSH or Linux Shell Commands – JustHost

ls : list files/directories in a directory, comparable to dir in windows/dos.
ls -al : shows all files (including ones that start with a period), directories, and details attributes for each file.

cd : change directory
cd /usr/local/apache : go to /usr/local/apache/ directory
cd ~ : go to your home directory
cd – : go to the last directory you were in
cd .. : go up a directory

cat : print file contents to the screen
cat filename.txt : cat the contents of filename.txt to your screen

tail : like cat, but only reads the end of the file
tail /var/log/messages : see the last 20 (by default) lines of /var/log/messages
tail -f /var/log/messages : watch the file continuously, while it’s being updated
tail -200 /var/log/messages : print the last 200 lines of the file to the screen

more : like cat, but opens the file one screen at a time rather than all at once
more /etc/userdomains : browse through the userdomains file.
hit Space to go to the next page, q to quit

pico : friendly, easy to use file editor
pico /home/burst/public_html/index.html : edit the index page for the user’s website.

vi : another editor, tons of features
vi /home/burst/public_html/index.html : edit the index page for the user’s website.

grep : looks for patterns in files
grep root /etc/passwd : shows all matches of root in /etc/passwd
grep -v root /etc/passwd : shows all lines that do not match root

touch : create an empty file
touch /home/burst/public_html/404.html : create an empty file called 404.html in the directory /home/burst/public_html/

ln : create’s “links” between files and directories
ln -s /home/username/tmp/webalizer webstats: Now you can display to show your webalizer stats online. You can delete the symlink (webstats) and it will not delete the original stats on the server.

rm : delete a file
rm filename.txt : deletes filename.txt, will more than likely ask if you really want to delete it
rm -f filename.txt : deletes filename.txt, will not ask for confirmation before deleting.
rm -rf tmp/ : recursively deletes the directory tmp, and all files in it, including subdirectories. BE VERY CAREFULL WITH THIS COMMAND!!!

last : shows who logged in and when
last -20 : shows only the last 20 logins
last -20 -a : shows last 20 logins, with the hostname in the last field

w : shows who is currently logged in and where they are logged in from.

netstat : shows all current network connections.
netstat -an : shows all connections to the server, the source and destination ips and ports.
netstat -rn : shows routing table for all ips bound to the server.

top : shows live system processes in a nice table, memory information, uptime and other useful info. 
This is excellent for managing your system processes, resources and ensure everything is working fine and your server isn’t bogged down.
Shift + M to sort by memory usage
Shift + P to sort by CPU usage

ps: ps is short for process status, which is similar to the top command. It’s used to show currently running processes and their PID.
A process ID is a unique number that identifies a process, with that you can kill or terminate a running program on your server (see kill command).
ps U username : shows processes for a certain user
ps aux : shows all system processes
ps aux –forest : shows all system processes like the above but organizes in a hierarchy that’s very useful!

file : attempts to guess what type of file a file is by looking at it’s content.
file * : prints out a list of all files/directories in a directory

du : shows disk usage.
du -sh : shows a summary, in human-readble form, of total disk space used in the current directory, including subdirectories.
du -sh * : same thing, but for each file and directory. helpful when finding large files taking up space.

wc : word count
wc -l filename.txt : tells how many lines are in filename.txt

cp : copy a file
cp filename filename.backup : copies filename to filename.backup
cp -a /home/burst/new_design/* /home/burst/public_html/ : copies all files, retaining permissions form one directory to another.
find * -type d|xargs -i cp –verbose php.ini {} : copies your php.ini file into all directories recursively.

kill: terminate a system process
kill -9 PID EG: kill -9 431
kill PID EG: kill 10550
Use top or ps ux to get system PIDs (Process IDs)


10550 pts/3 0:01 /bin/csh
10574 pts/4 0:02 /bin/csh
10590 pts/4 0:09 APP

Each line represents one process, with a process being loosely defined as a running instance of a program. The column headed PID (process ID) shows the assigned process numbers of the processes. The heading COMMAND shows the location of the executed process.

Putting commands together
Often you will find you need to use different commands on the same line. Here are some examples. Note that the | character is called a pipe, it takes date from one program and pipes it to another.
means create a new file, overwriting any content already there.
>> means tp append data to a file, creating a newone if it doesn not already exist.
send input from a file back into a command.

grep User /usr/local/apache/conf/httpd.conf |more
This will dump all lines that match User from the httpd.conf, then print the results to your screen one page at a time.

last -a > /root/lastlogins.tmp
This will print all the current login history to a file called lastlogins.tmp in /root/

tail -10000 /var/log/exim_mainlog |grep |more
This will grab the last 10,000 lines from /var/log/exim_mainlog, find all occurances of
(the period represents ‘anything’, comment it out with a so it will be interpretted literally), then send it to your screen page by page.

netstat -an |grep :80 |wc -l
Show how many active connections there are to apache (httpd runs on port 80)

mysqladmin processlist |wc -l
Show how many current open connections there are to mysql

mysqldump -u username -p dbname > file.sql
MySQL Dump

mysql -u username -p database_name <file.sql
Importing MySQL database

tar -zxvf file.tar.gz
UnTAR file

Finding path to

Concepts in Programming Languages – University of Cambridge Course

The following are all copy and pasted from a University of Cambridge course link to the website below. It was accessible by public, so I figured I should dump it here. Maybe I can read some of this when I have a vacation.

Lecture slides

  • Introduction and motivation.
    Additional reading material:
  • K. ZusePlankalkul.
  • The first procedural language: FORTRAN (1954-58).
    Additional reading material:
  • Fortran.
  • The first declarative language: LISP (1958-62).
    Additional reading material:
  • J. McCarthyRecursive functions of symbolic expressions and their computation by machine.
    Communications of the ACM, 3(4):184-195, 1960.
  • Block-structured procedural languages: Algol (1958-68) and Pascal (1970).
    AppendixBCPL (1967) and C (1971-78)
    Additional reading material:
  • D. E. KnuthThe remaining trouble spots in ALGOL 60.
    Communications of the ACM, Volume 10, Issue 10, pages 611-618, 1967.
  • B. KerninghanWhy Pascal is not my favorite programming language.
    AT&T Bell Laboratories. Computing Science Technical Report No. 100, 1981.
  • Object-oriented languages — Concepts and origins: SIMULA (1964-67) and Smalltalk (1971-80).
    SML codeObjects in SML!?
    Programming languageSqueak.
    Additional reading material:
  • A. C. KayThe early history of Smalltalk.
    ACM SIGPLAN Notices, Volume 28, No. 3, 1993.
  • P. WegnerConcepts and Paradigms of Object-Oriented Programming
    Expansion of OOPSLA-89 Keynote Talk.
  • B. StroustrupWhat is Object-Oriented Programming? (1991 revised version).
    Proc. 1st European Software Festival. February, 1991.
  • Types in programming languages: ML (1973-1978).
    Additional reading material:
  • A. Koenig. An anecdote about ML type inference.
    USENIX Symp. on Very High Level Languages, 1994.
  • Data abstraction and modularity: SML Modules (1984-97).
    Additional reading material:
  • M. TofteFour Lectures on Standard ML.
    LFCS Report Series ECS-LFCS-89-73, 1989.
  • The state of the art: Scala (2004-2006).
    Programming languageScala.
    Additional reading material:
  • M. Odersky et alAn overview of the Scala programming language.
    Technical Report LAMP-REPORT-2006-001, Second Edition, 2006.
  • M. Odersky et alA Tour of the Scala Programming Language.
    Programming Methods Laboratory, EPFL, 2007.
  • M. OderskyScala By Example.
    Programming Methods Laboratory, EPFL, 2008.
  • Books

  • Main:
  • M. ScottProgramming Language Pragmatics (2nd edition).
    Morgan Kaufmann, 2006.
  • J.C. MitchellConcepts in programming languages.
    Cambridge University Press, 2003.
  • T.W.Pratt and M.V.ZelkowitzProgramming Languages: Design and implementation (3rd edition).
    Prentice Hall, 1999.
  • Other:
  • R. L. Wexelblat (ed.). History of Programming Languages.
    ACM Monograph Series, 1981.
  • N. Metropolis, J. Howlett, G.-C. Rota (eds.). A History of Computing in the Twentieth Century: A Colletion of Essays.
    Academic Press, 1980.
  • T.J. Bergin and R. G. Gibson (eds.). History of programming languages – II.
    ACM Press, 1996.
  • [Actual Course Website]

    It’s all about the SCRUM Master hat.

    This is a great video that explains scrum development. It is something I want to use personally when my current programming team gets a little bigger.

    This following is the introduction to Scrum Development on Wikipedia:

    Scrum is an iterative, incremental framework for project management often seen in agile software development, a type of software engineering.

    Although the Scrum approach was originally suggested for managing product development projects, its use has focused on the management of software development projects, and it can be used to run software maintenance teams or as a general project/program management approach.