Linux Essentials 010 160
______________ __ preserve the literal value of *most characters* contained within the quotes, exceptions include *$* (for variables), *'*(for single characters) and *\*(for escaping a character)
"" Double quotes
when dealing with regular expressions, if I wanted to match the end of a line i would add a $
$ example // Apple$
You're unable to exit the vi editor without saving the changes made to the file by using the :q command. Why?
! is not appended with the command. The :q command only exits the file if the changes are saved.
piping allows what?
The user to feed in the results of one command into another command.
using man -k is the same as using
apropos "KEYWORD"
tar f
file name type of archive file
| (pipe) command in Regular expressions does what?
logical OR between two patterns
a user wants to view hidden files in a directory
ls -a
a user wants to display file information in a human readable format
ls -h
a user wishes to see a long listing view of files and their permissions
ls -l
a user wishes to see a listing of size of their files
ls -s
zip and name a file trip.zip with max compression
zip -9 trip.zip arbitrary_file.txt
If i wanted to alphabetize the results of cat apple_results.txt what would succeed the file name?
| sort pipe sort command
bash operator OR
||
what is the result of utilizing a question mark (?) in the cmd line?
Matches up exactly one character
what is "read" in bash scripting
same as cin in c++ takes input from keyboard
what is found in the etc/resolv.conf
search nameserver domain
How can you browse to a new node using the standard info documentation reader?
select hyperlink with arrow keys and enter button for selection
which sort option will you use to specify a target file?
sort -o
tar t
t- view content of archive file
to determine the number of files and folders?
wc -l (wordcount -lines)
what does the ./ denote in a command or script
we can run it from here the current directory
which CPU types does Linux run?
x86 ARM x64
__________ is used to preserve the literal value of *every character* contained within the quotes, including the escape character
' ' Single quote
tar j
--xz
If i wanted to redirect the output of the cat and grep commands, what would succeed the pattern Apple? cat american-english | grep Apple
> apple_results.txt
If i wanted to redirect and append the output of the cat and grep commands, what would succeed the pattern Apple? cat american-english | grep Apple
>> apple_results.txt
memory leaks lead to what?
A program keep requesting for more memory a program failing to return memory after it is done with it
three command modes in vi
Ex Command Insert
Which of the following statements are true of functions in Linux scripts?
Fn's can be declared by using the fn keyword A fn is called by its name in a script similar to an ordinary command
cut command does what
Prints selected parts of lines from each file to output
cut -d
Prints selected parts of lines then delimits (cuts) a portion of text with some character
observe cat american-english | grep -E "Ap*le" What does the "Ap*le" expression mean?
That there will be 0 or more Ps in the phrase "Ap*le"
observe cat american-english | grep -E "Ap+le" What does the "Ap+le" expression mean
That there will be 1 or more P s in the phrase "Ap+le"
observe grep -E What does the option -E denote?
The allowing of regular expressions
Only root may change a file's ownership with chown.
True
grep -E, allows what?
Use of regular expressions in the grep command
id command displays?
Username Group memberships UID
chmod o+t subdir
You want to set the sticky bit on an existing directory, subdir, without otherwise altering its permissions
a non quoted _______ is the ______ and preserves the *literal value of the next following character * with the single exception of newline "n"
\ Escape Character
userdel -f
deletes a user that is currently logged on
which command deletes a group in linux
delgroup
A user enters the etc/passwd file and wishes to output the string :/home/michael. the entire strings reads michael:x:1000:1000:michael christian...:/home/michael:/bin/bash what series of piped commands must he enter to output this string
cat etc/passwd | grep michael | cut -d: -f6
command to change a files group
chgrp chown
What command would you type (as root) to change the ownership of somefile.txt from ralph to tony?
chown tony somefile.txt
tar z
compressed gzip archive
useradd -r
creates a system account (has no directory)
tar c
creates an archive file
chmod +x does what to a script
gives user, group, other executable writes
grep command for displaying number of matching lines in a file
grep -c
input redirection example
grep Apple < sorted.txt
output redirection example
grep Apple > sorted.txt
Which of the following commands is used to view a list of most recent commands executed by a user?
history
a user wants to display the list of all the users logged in and out since the file /var/log/wtmp was created
last
you want to narrow a search in man for keywords
man -k "KEYWORD"
what is the result of uytilizing an Asterisk (*) in the cmd line?
match any number of character(s)
A user must utilize "Globbing". What is globbing?
methods used to match patterns in filenames or text by using a wildcard character to create a pattern.
sets the number of pings sent in linux
ping -c
grep -E ^M american-english
prints out words starting with M in the file american-english
tar command what does rf mean and do
r - append f - file name
userdel -r
removes a users home directory AND deletes the account
tar x
to untar or extract use, the x
a user wants a list of running processes, what command should she use
top- shows tasks ps- shows processes
what is used to set default file permissions for newly created files
umask
A user wants to check what kernel release he has, what cmd should he use
uname -r
A user wants to check what kernel name he has, what cmd should he use
uname -s
A user wants to check what version his kernel is running on, what cmd should he use
uname -v
what is the | pipe used for?
used for applying more than one condition
what is the ($) used for?
used to match ending character
what is the {} curly brace used for?
used to match more than one pattern
what is the caret (^) used for?
used to match starting character
tar v
verbosely state .tar file progress
a user wants to check all the current users logged on to a Linux machine what cmd should they use?
w
to count the number of words
wc