UNIX Commands ~ Quiz 1/22/25

pwd

show the current working directory

man

display the manual for a command

ls

list files and directories

ls -l

display detailed information about files and directories

ls -a

list all files, including hidden files

ls -lrt

list files sorted by modification time in reverse order

ls -alh

display detailed information including hidden files in human-readable format

clear

clear terminal screen

cat

concatenate and display file contents

cat -n

number all lines of the output

cat >

create a new file and write to it

cat >>

append text to an existing file

head

show the first few lines of a file

head -20

display the first 20 lines of a file

tail

show the last few lines of a file

more

view file contents one screen at a time; basic

less

view file contents with scrolling; advanced

diff

compare two files line by line

cd

change current directory

mkdir

create new directories

rm

remove files or directories

rm -r

remove directories and their contents recursively

rm -i

prompt before every removal

rm -f

force removal without prompting for confirmation

rmdir

remove empty directories

cp

copy files or directories

cp -r

copy directories and their contents recursively

cp -i

prompt before overwriting files copy

cp -f

force copy by overwriting files without prompting

chmod

Change file permissions by using 3 digit code

Read: 4, Write: 2, Execute: 1

First digit: Owner’s permissions; Second digit: Group’s permissions; Third Digit: Others’ permissions

You add them based on what you want the permissions to be: 755, 777, 644, 600, 400

chmod -R

change permissions recursively for directories and their contents

mv

move or rename files and directories

mv -i

prompt before overwriting files

mv -f

force move by overwriting files without permission

wc

count lines, words, and characters in a file

wc -l

count number of lines

wc -w

count number of words

wc -m

count number of characters

df

display available disk space on file systems

df -h

show disk space usage in human-readable format

top

show real-time info about system processes

ps

list currently running processes

ps aux

display detailed information about all processes

grep

search for patterns in files

grep -n

display matching lines with their line numbers

grep -i

search for patterns in a case-insensitive manner

grep -c

count number of matching lines

grep -w

match whole words only

egrep

enable extended regular expressions

grep -m

limit the number of matches displayed

grep -color

highlight the matched text in color

grep -rl

search for matching text recursively in files and output filenames

grep -o

display only the matched text

sort

sort lines of text in a file

sort -r

sort in reverse order

sort -k

sort based on a specific key or column

sort -f

ignore case while sorting

sort -o

save sorted output to a file. Can be used for in-place sorting.

sort -n

perform numeric sorting

paste

merge lines of files

paste -s

merge all lines into a single line

paste -d

specify a custom delimiter for merging

cut

remove sections from each line of a file

cut -d

specify a delimiter for field separation

cut -f

specific specific fields to display

cut -c

select specific character positions

join

join two lines of two files on a common fieldj

join -a

include unpaired lines from one or both files

join -t

specific a custom delimiter for joining fields

echo

print text or the value of variables to the terminalsu

su

switch to another user

sudo

execute commands as the superuser or another user

touch

create or update the timestamp of a file

history

show command history

reset

reset the terminal to fix display issues

alias

create shortcuts for commands

unalias

remove shortcuts for commands

sed

perform text substitution, deletion, and line-based editing

sed ‘s/<pattern>/<replacement>/gi’

substitute all matches ignoring case, applying globally

sed -i’.bak’

edit in place, creating a backup with the .bak extension

sed -n’/pattern/p’

print only lines that match the pattern

sed’/pattern/d’

delete lines that match the patternse

sed’y/<oldchars>/<newchars>/’

translate characters one-to-one

sed -e

combine multiple editing commands in a single executions

sed -f

execute sed commands from a file