LPIC-1 C3 Commands

.tar cvf archivname.tar /home/myname/mydirectory/*

# Create a tar archive of all files in a particular directory; c = create; v = verbose... filename details; f = name of archive being created... must be last

pr -d -l 10 filename

-d adds a space in between lines; -l sets the max nbr of lines to print per screen

cat -n /etc/passwd

-n prints to the screen with number lines

Normal mode

Also known as command mode; Default mode accessed by pressing Esc key while in insert mode

sort /etc/passwd

Arrange lines in alpha order

nice -10 apt-get install apache2

Assign value 10; Equivalent to run when resource demand is low

nice --10 apt-get install apache2

Assigns a negative nice value; Places a priority on running the process and using resources

nice

Assigns linux resources based on assigned value between 19 and -20; 19 = nice; -20 = nasty

grep non regex characters

Backslash \ Caret ^ Dollar sign $ Dot . Pipe symbol | Question mark ? Asterisk * Plus sign + Parentheses () Square brackets [] Curly braces {}

What type operations are used within vi command line mode?

Basic file management

fg [job_spec]

Bring job [job_spec]to the foreground from background; Continue a stopped job by running it in the foreground

How would grep interpret metacharacters as literal characters?

By placing string inside quotations; precede metacharacter with a backslash \

renice -10 -p 3745

Change nice value of process 3745 to 10

metacharacter

Characters that have a special meaning; example: ^, $, *

:q command line operation

Close vi without saving the current file

paste

Command to merge contents of multiple files

Unexpand

Convert (every # of specified) spaces to tabs

cat /etc/passwd | tr "a-z" "A-Z"

Convert all lowercase to uppercase

unexpand -t 3 filename

Convert every tab to 3 spaces

expand -t 10 filename

Convert tabs to 10 char (spaces) apart

expand

Convert tabs to spaces

dd if=/dev/sdb1 of=/media/usb/partitionbackup

Copy a partition called sdb1 to usb partition called partitionbackup

cp

Copy command

cp myfile /home/myname/Desktop/

Copy file myfile to Desktop directory

scp filename [email protected]:/home/myname/ && rm filename

Copy filename to a remote system; Delete the original only if the copy was successful

sudo find ./ -maxdepth 4 -name "*.txt" | cpio -o > /home/ubuntu/archivename.cpio # created similar to previous tar, but with cpio

Create archive with cpio; Find at root level, 4 levels down, files .txt extension; Pipe thru xargs which allows command execution on streaming data; Create a new .cpio archive

sudo mkdir /etc/newdir

Create with root access privileges

sudo mkdir -p /etc/path/to/mydirectory/

Creates a nested hierarchy of directories

mkdir

Creates a new directory

mkdir newdir

Creates a new directory named "newdir' in current dir

touch

Creates a new, empty file and updates access time metadata

echo $USER

Display current account name populated with USER variable

echo $PWD

Display current working directory

wc

Display document statistics... word and byte counts

top

Display information about running processes and who's running them

env

Display list of current variables... not local or functions

wc /etc/passwd

Display total number of lines, words and bytes in specified file

kill -l

Displays all signals available and their value

file

Displays file details

history

Displays the content of .bash_history file

history | grep .bash_history

Example... This would display the occurrence of ".bash_history" within the .bash_history file.

How would you create a local variable "myvariable"?

Example... myvariable=hello

xargs

Extended arguments... can build and execute command lines from standard input

egrep

Extended grep; Has a larger list of characters it reads as metacharacters

.bash_history file

File where command history is saved

fmt -t filename

Indent all but the first line of a paragraph

screen

Lets you multiplex terminal windows; Allows running mor than one process from a single terminal; May have to install (sudo apt-get install screen)

jobs

List all processes running in the background of current shell

ls -l | tee list.txt

List contents of current directory with details; tee command (as in T splitter) pipes output to multiple targets... including list.txt and stdout

ls

List files and directories

ls -lh

List files and file attributes; Human readable

ls -a

Lists all files including hidden ones... those identified with a "." in front of their name

pgrep

Look up signal process based on name

join

Merge two files with overlapping columns; ex: join column1 column2

mv myfile /home/myaccount/Desktop/

Move file myfile to new location and keep same file name

mv

Move files... the original file is deleted

vi modes of operation

Normal (command); Insert; Command line

When are variables available, when created in Bash session?

Only in current Bash session

uniq -u text.txt

Only print lines that are not repeated

uniq

Only prints lines unique to the file... file needed to be sorted for this to work

tail

Output the last part of a file (10 lines)

join column1 column2 > newfilename

Output to new file

:w! command line operation

Overwrite the existing file

ls | cpio -0 > myarchivename.cpio

Pipe output from list directory command to create archive

ls | cpio -0 | gzip > myarchivename.cpio.gz

Pipe output from list directory command to create archive; Add compression with gzip

How do you access Command mode within vi while in insert mode?

Press Esc key

paste -s column1 column2

Print files sequentially

sort -n /etc/passwd

Print lines in numeric order

sort -r /etc/passwd

Print lines in reverse alpha order

cat -n /etc/passwd | sort -nr

Print lines in reverse numeric order

tail -f /var/log/syslog 1> log-data.txt

Print new entries to syslog file and pipe the standard output to a file

head -10 filename

Print only first 10 lines of a file

uniq text.txt

Print only the first time a repeated line appears

tail -n 3 /etc/passwd

Print only the last 3 lines of the passwd file

od

Print text file in octal format; ex: od filename

The head and tail commands, allow you to view the first few or last few lines of a file (____ lines by default).

Prints only a specified number of lines from front or back end of a file

:q! command line operation

Quit without saving changes

cut -d: -f1 /etc/passwd

Reads the passwd file; Sets a delimeter as a colon (-d:) so when a colon appears in the text, cut will then start a new text field; Print only the first field of every line (-f1)

sort

Rearrange how lines are displayed

sudo cp -r /home/myname/mydirectory/ /usr/share/place/

Recursive argument (-r) copies everytthing in and beneath "/mydirectory/" to /usr/share/place

tar cvf newarchive.tar /dev/sdb1 2> error.txt

Redirect error text output to file error.txt; Create archive; Verbose... list files processed; Filename of archive you're creating

regex

Regular expression; A sequence of characters understood to be either metacharacter (special meaning) or regular character with literal meaning

rm -r *

Removal acts on all the files in a directory

rm

Remove files and directories; ex... rm myfile

rm -r newplace

Removes the directory and its files

mv myfile newname

Results in file myfile being renamed to file newname

apropos

Returns the names of all man files that seem relevant to search string used with the command; Example... apropos zip would return names of relevant files

:w command line operation

Save the current file to disk... will prompt for filename

ls | grep "(this"

Search for file names that include the string "(this"

ls | grep \(this

Search for file names that include the string "(this"

scp

Secure remote file copy;

killall <processname>

Sends kill signal to all processes for identified process name

free

Show how much RAM is being used

free -h

Show megabyte and gigabyte info

Common kill signal values

Signal 1 = sighup... parent shell is closing ("signal hang up"); Signal 2 = sigint... interrupt, which is same as Ctrl-c; Signal 9 = sigkill... shutdown; Signal 15 = sigterm... terminate signal

fmt

Simple text formatter which formats how text is printed to the screen

cut -d:

Specifies that a colon (:) will be a field delimeter

bg [job]

Specify job you want to run in the background

split -2 filename

Splits file into multiple files of two lines each... named xaa, xab, xac, ...

stderr

Standard error defined by 2

stdin

Standard input defined by 0

stdout

Standard output defined by 1

fmt -w 60 filename

Start a new line after 60 characters

kill <pid>

Stops process ID listed with the command

cat filename 2> errors.txt

Stream contents of filename and pipe stderr output to a file; If no error, output file will be empty

sed

Stream editor command for filtering and editing text

cat text.txt | sed s/hello/"goodbye"/g

Substitution is done globally for all occurrences of the specified word

cat text.txt | sed s/hello/"goodbye"/

Takes input from a stream via cat and substitutes a specified word for the first occurrence; Replaces "hello" with "goodbye"

.tar

Tape archive

.less

Text reader program used to view files instead of opening them

tr

Transform text

fgrep (grep -F)

Treats all characters as literal; Works quickly

How do you access vi insert mode while in normal mode?

Type i followed by Enter key

How do you access vi command line mode?

Typing a colon ":" and pressing Enter key

Breakdown the following command: sudo find . -maxdepth 4 -name "*.txt" | xargs tar cvf textarch.tar # use tar on data streams

Use find at root level; Down 4 levels; For files with names that include .txt extension; Pipe thru xargs which allows command execution on streaming data; Create a new archive textarch.tar

.bz2

bzip2 uses what extension

split

command to divide a single file into mult files of specified length

dd

convert and copy a file

cpio

copy files to and from archives

unset

deletes variables

uname -a

display Linux kernel and installation information

How would you display the content of locally created variable "myvariable"

echo $myvariable

How would you make a local variable available for new shell sessions?

export command; Example... export myvariable

Alternate way to write egrep command

grep -E

.gzip

gzip and gunxip uses what extension

ls -s

lists files and subdir in long form

e

r

renice -10 -u tony

renice applied to processes associated with user tony

renice -10 -g audio

renice applied to processes owned by a particular group... "audio" in this example

ps

report a snapshot of the current processes; Displays all processes used by current shell

sudo cp myfile /home/anothername/Desktop/

root access needed to copy to a location outside your acct

cut -d

specifies a character to be used as a field delimiter; The default is a tab

Three streams open for linux commands

stdin stdout stderr

rm -ri newplace

the i makes the process interactive and will prompt you, to confirm this is what you want to do

q

w

pr

Formats text files for printing

:e! command line operation

Walk back changes since last write

x; ex. tar xzvf archivename.tar.gz

What parameter is used to decompress and extract files from a .tar tape archive?

add z... ex tar cvfz arvchivename.tar ...

What parameter would add compression to tape archive

Rm file?

Will delete any file that contains the word file and any additional characters

rm file?

Will delete files that contain the word file and any single additional character

paste column1 column2

Without arguments, prints files side by side

:exit command line operation

Write the current file and exit vi editor

:wq command line operation

Write the current file, then exit; Same as :exit

.xz

Xz uses what extension