Chapter 1 Flashcards
Shell
Program that accepts and interprets text-mode commands and provides an interface to the system
4
Environment variables
placeholders for data that may be useful to many programs
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bash
most common default shell for user accounts
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sh
the Bourne shell
4
tcsh
based on csh (a C shell). No major distros. similar to bash
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csh
the original C-shell
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ksh
the Korn shell. Bourne shell and the C shell extended
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zsh
the Z shell takes the Korn shell to the next level
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2 types of default shells
default interactive shell
default system shell
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/bin/sh
a pointer to the system’s default system shell
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uname
command showing which OS is being run
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cd
change directory
6
~
home directory
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echo
displays the text that you enter
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time
tells you how long the system took to execute a command
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set
displays a wide variety of options relating to bash shell operation. These options are formatted much like environment variables, but they aren’t the same things.
7
exit vs logout
exit terminates any shell
logout terminates only login shells
7
Login shells
shell programs that are launched automatically when you initiate a textmode login as opposed to those that run in xterm windows or on other terminal emulators
7
-a
shows if there are internal commands with installed duplicate external commands
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what happens when you type a command that the shell does not recognize as one of its internal commands?
the shell checks its path to find a program by that name to execute it
8
command completion
type part of the command or a filename (as an option to the command or filename and press tab and the shell fills in the rest of it
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How long can filenames be?
up to 255 characters
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Retrieve command
Pressing the up button on the command line. It repeats the previous command. Guess what down does.
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backward/reverse search
Press Ctrl+R and begin typing characters that should be unique to the command from anywhere inside the command
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forward search
Ctrl+S reverses the search from backward to forward.
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What do you do if Ctrl+S causes a hang?
Ctrl+Q resumes terminal function
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Ctrl+A
moves the curser to the start of the line
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Ctrl+E
moves the curser to the end of the line
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Ctrl left/right
moves the curser left or right by a word
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Ctrl+D/delete
deletes the character under the curser as apposed to behind it
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Ctrl+T
transposes the character before the curser with the character under the curser
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Esc then U
Changes the letters between the curser and the end of the word to uppercase
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Esc then L
Changes the letters between the curser and the end of the word to lowercase
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Ctrl+X then Ctrl+E
launches a text editor
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history
displays all of the commands in the history up to 500
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!
executes the command that corresponds to the number that follows it
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man
loads the manual entry on how to use a command
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info
a manual in hypertext format
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