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Absolute Pathname

starts with a slash (/), which represents the root directory. The slash is followed by the name of a file located in the root directory. An absolute pathname can continue, tracing a path through all intermediate directories, to the file identified by the pathname. String all the filenames in the path together, following each directory with a slash (/). This string of filenames is called an absolute pathname because it locates a file absolutely by tracing a path from the root directory to the file.

Relative Pathname

traces a path from the working directory to a file. The pathname is relative to the working directory. Any pathname that does not begin with the root directory (represented by /) or a tilde (~) is a relative pathname

3 ways to return to your home directory

cd ~, cd, cd $HOME

What‘s the arrangement of directories and files in the unix system?

a tree-like structure called the file system, called a directory tree. At the very top of the file system is a directory called “root” which is represented by a “/”. All other files are “descendants” of root.

What directory does it take you to when you first log in?

The home directory.

What’s the command that gives helpful information on a utility?

man (eg: ‘man cat’ will display a manual on the cat utility)

What symbol do hidden files in a directory start with?

dot character (.)

What’s the command that tells you the current name of the shell?

echo $0 (returns -bash)

Set a variable value in a borne shell. How do you display the variable?

echo $variname

What does echo $PATH display?

Which directories your shell is set to check for executable files. $PATH is the list of said directories.

What is the command and option that lets you see all the meta information of a file?

ls -l filename

Inside a borne shell script, what’s the symbol used for the PID?

$$

What’s the command that can be used to change permission information for a file?

chmod

syntax: chmod a+r filename (makes filename readable to all)

What’s the command that copies files?

cp

syntax: cp ogfile copyfile

What’s the command that is used to tell the type information of a file?

file

eg: file filename (displays filename: ASCII text)

What’s the command used on a file to display one page of information of the file contents at a time?

more or less (less allows you to scroll up, more does not)

eg: cat filename | less

What’s the command to make soft links?

ln -s filename linkname

Allows multiple filenames to be linked to a file

What’s the command that outputs the contents of a text file?

cat filename

What’s the command that searches for patterns in a text file?

grep string filename

Basic redirection syntax.

cat >  filename

Create a file called filename. Type the desired input and press CTRL+D to finish. The text will be in file filename.

cat < filename

Just cats the content of filename.

What is the command that makes a new subdirectory/directory?

Mkdir dirName

What’s the command that removes a file? Moves a file?

rm filename

mv filename newfile

What’s the command that displays the information about the users logged into the system?

who

What’s the command that deletes a non-empty directory?

rmdir or rm -d

If I touch a file name, and the file name doesn't already exist, does touch create it?

Yes, touch creates an empty file.

If you set the variable value in the shell and you want a program/script to read and display it, what command do you have to do on the variable to make it available to the script?

export

How do you read in a value in a shell prompt?

read

What does the command “find” do? find -name?

used to find files and directories and perform subsequent operations on them. It supports searching by file, folder, name, creation date, modification date, owner and permissions.

find -name searches filenames specifically.

What is the command to list all the files in your working directory that start with a dot?

ls -a lists all files including hidden files that start with a dot. do not try ls .* it broke my thing

Metacharacter for pipe?

|

Which key stroke will enter command mode in VIM?

esc

in VIM, which keystroke will allow you to enter editor mode?

i

What mode is VIM in at first?

command mode

Command to write (save) the contents of the files then quit the editor?

esc :wq!

What symbols do commands start with in VIM?

:

Can you chmod a file you don’t own?

No

Can you list metadata on files you don’t own?

Yes

What is a root?

A user that can do anything (ex: chmod any file)

What does touching an already existing file do? Does it reset it’s permissions?

if the file existed beforehand, touch will not change its permissions, just update its last edited timestamps

What is a token?

What symbol do options start with?

-

Identify commands with 0 arguments.

cd, pwd

What is an example of a built-in command?

echo, cd

How do you do piping?

A pipe is a form of redirection (transfer of standard output to some other destination). Allows you to use 2 commands at once

ex: history | tail

calls history command and tail to display the last 10 executed commands

What’s the comments you need on the first line of the script to ensure it gets executed on the bash shell?

#!/bin/bash

What are the 2 metasymbols you have to put at the beginning of a script for it to run correctly?

./

What’s the syntax for creating an alias?

alias ‘someAlias=someCommand’

What does grep do? Syntax?

Identifies line with requested string.

grep “l” filename

works on directories to search file names

Which file do you save variables, functions, and aliases to so they are available upon log in?

In the ~/.bashrc file

What are the single dot and double dot directory entries?

mkdir automatically adds these 2 entries.

The . is synonymous with the pathname of the-working directory and can be used in its place; the .. is synonymous with the pathname of the parent of the working directory. These entries are hidden because their filenames begin with a period.

num=875

number1=”Add $num”

number2=’Add $num’

What will echo $number1 and echo $number2 display?

Add 875

Add $num

ls -l info idk just memorize this

chmod symbols (just memorize this too)

Do I have to put symbols in front of a function name to run it or can I just put the name of the function?

Just name of function.

What is the shell metacharacter that matches 0 or more characters?

*

What is the shell metacharacter that matches 1 character?

?

Inside a script, what are the symbols that contain the arguments on the command line to the script?

$1, $2, … , $n for each argument n on the command line