<< Back: Part 3 <<

Week Two Quick Reminders
[some of the topics and commands covered]

Directory Reminder Notes from Lesson Two:

home - user's main directory
public_html - where web documents reside. Contents viewable online.
www - reference back or mirror to public_html. Not difference in color in default PuTTY settings. Known as a symbolic link.
bin - normally binary executable files
etc - system configuration files and settings
tmp - temporary files
var - system logs, user mail and other temporary data
lib - libraries
usr - sub-directories may include:
- /usr/bin - commands and programs [not as important to UNIX as bin/]
- /usr/local - customized files and data
- /usr/local/bin - locally installed programs
- /usr/local/man - the manual for local programs
- /usr/share - resources shared by more than one user account

Some Basic Unix Commands & Flags

pwd [print working directory]
- . current directory
- .. parent directory
ls [list]
- ls -C [columns....I see no change on my server]
- ls -F [identify slash = a directory * = an exe file @ = soft/symbolic link]
- ls -a [all]
- ls -x [format across]
- ls -R [recursive - show all files in sub-directories as well]
- ls -t [recently modified]
- ls -l [listing permissions long format see part 2 of the lesson.]
***Flags can be combined*** Example: ls -axF

cd [change directory]
- cd ~ [takes you to your home directory from anywhere. plain cd will get you there as well on my current server]
- cd .. [takes you up one level]
- cd ../.. [takes you up two levels]
- cd directory-name [takes you to the named directory]
- cd directory-name ; ls [commands divided by semi-colon both executed] cd ls -aF directory-path [list contents of a directory you are not physically inside..flags optional]

tree -d . [layout of directory/ies displayed. Not space and period . at end]
cat [to read a specific file]
more [similar to cat but delivered in small, screensized chunks]
less [similar to more, but does not exit file until you manually input Q to quit]
passwd [to change password]

Basic Shell Information

sh - Bourne Shell [dates from 1979 still in use]
csh - C Shell [commands similar to C programming language]
ksh - Korn Shell [new features to improve workflow. commercial product]
bash - Bourne Again Shell created 1988 [open source/GNU. standard with most Linux systems said to be most versitile and user friendly shell setup]
tcsh - Variation of the C Shell with more options. Said to be more user friendly

Environmental Variables

<< echo >> command - [print or echo the output to your terminal. follow it with an enviromental variable such as those below]
- $SHELL
- $BASH_VERSION

Finding Other Shells & Moving to Them Temporarily

First place to check is /etc/shells . Try using the << cat >> command here.
If they are not there, try the same process or ls in directories like /usr, usr/bin or usr/local/bin.
Example: ls /usr/local/bin/*sh
To temporarily move to another shell, type the name at the bash $ prompt.
Example: $ /bin/tcsh
Reminder: Be sure to exit a shell you are temporarily visiting.

History

Used to review and/or repeat commands

Scroll up or down using the up and down arrow keys. When the command you want is found, hit the enter key.
<< history >> - [gives list of all commands]
<< history 25 >> - [lists set number of past commands indicated by number]
!57 - [repeats command indicated by number]
!! - [repeats last command]

Arithmetic

<< expr >> followed by any combination of the following:
- + for addition
- - for subtraction
- \* for multiplication
- \/ for division

Finding Information

apropos [need a function? type in what you want to do after this command and it will give you lists of options]
whatis [brief definitions]
info [more detailed information. manual with menu interface]

The Ctrl Key can be used to access the help menu. Ctrl+H is the command used. The letter C or a caret ^ [aka a cat ear] normally represent this key. C-h would be the normal command.