EMT 2390L Lecture 2 Dr. Reyes

Outline What is the Shell Basic commands Linux Filesystem System commands

What is the Shell? Shell - a program that takes keyboard commands and passes them to the operating system to carry out Types of Shells: o C-Shell: csh, tcsh o Bourne Shell: sh o Bourne Again Shell: bash When using a GUI, a terminal emulator is used to interact with the shell o KDE uses konsole o GNOME uses gnome-terminal

Shell Prompt

Session Privileges Prompt ending with: o $ - regular user, privileges varies o # - superuser

Command History Press up-arrow key for previous command Press down-arrow key for next command Press left-arrow key to move back in the same line Press right-arrow key to move back in the same line Limited support for mouse interaction Some keyboard shortcuts might not work, as they belong to Windows: o Ctrl-C o Ctrl-V

Commands Try the following commands: o date – displays the date o cal – displays the calendar o df – disk available o free – memory available o exit – to exit the system

Filesystem Tree Linux uses hierarchical directory structure o Tree-like structure o Root – First directory o Drives are not separate trees, instead they are mounted o You can see the files and the parent of the current directory o Each user account is given it’s own home directory

Commands for Directories pwd - lists the current working directory ls – lists the files and sub-directories in the current working directory cd – change to the specified directory o cd /usr/bin – changes to dir /usr/bin o cd / - changes to root dir Special parameters o. (dot) – current directory o.. (double dot) – parent directory o - (dash) – changes to the previous working directory o ~ (tilde) – changes to your home directory o ~username – changed to home directory of username

Linux Filenames Facts Filenames that begin with a period character are hidden. To display them use ls –a Filenames are case sensitive In Linux there are no file extensions such as.doc or.exe Avoid using spaces and special characters even if is supported.

Other uses of ls Try the following options with ls o ls /usr o ls ~ /usr o ls – l Most commands have options and argument o command –options arguments o options might be a dash and a single character or two dashes followed by a word

ls Options

ls –l What all that means?

Commands for files To get the file type o file filename To read a file o less filename o less is better than more

Some Linux Directories

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