cal - Shows calender
date - Displays date
clear - Clears terminal window
sort - Sorting function
man - Manual page for a certain command - Hit h for help on naviating a
manual page
man -k dog - Search the man pages of 'dog' and prints the related man pages
man 5 passwd - Retrieves the 5th chapter in the 'passwd' man page
echo - Prints out the argument
passwd - Command for changing password
which - Writes out the path to the program you reference in argument
pwd - Writes out the current working directory
type - Writes out the type of a program / command
whoami - Returns your username
who - Returns system information, for example, which users are logged in.
ls - Lists the contents of a directory
ls -a - Lists all contents.
ls -l - Lists contents of a directory, extended information
cd - Change directory
touch - Creates a new file
file - Determines the file type
rm - Removes files and directories
mv - Moves/renames files and directories
cp - Copy files and directories
CTRL-l - Clears the screen (Same as clear)
CTRL-a - Move cursor to the beginning of line
CTRL-e - Move cursor to the end of line
CTRL-f - Move cursor to the right - Same as right arrow key
CTRL-b - Move cursor backward - Same as left arrow key
Alt-f - Move cursor forward one word
Alt-b - Move cursor back one word
CTRL-t - Swaps character under cursor with left character
Alt-t - Swaps word under cursor with word to the left
CTRL-k - Delete everything on the right to the cursor
CTRL-u - Delete everything on the left to the cursor
alt-d - Delete the text from the cursor though the end of the word
CTRL-w - Delete the text from the cursor though the beginning of the word
CTRL-y - Yank (paste) after deletion/kill
history - See command history
history | less - Scroll command history
!X - Run command number X in history
CTRL-r - Search shell history of commands
cat - Prints the contents of a file
cat file1 file2 - Concatenates file1 and file2 and prints it out
less filename - Scroll though filename
tac - Same as cat but prints file in reverse order (starts at end)
rev - Prints contents of a file, reversing order of each line
head filename - Prints the head of filename, usually the 10 first lines
tail filename - Prints out the end of the filename, usually the 10 last lines
/var/syslog - System log
wc file - Prints out number of lines, number of words, number of bytes and
filename
wc -l file - Prints only the number of lines
wc -w file - Prints only the number of words
sort filename - Sorts the content of a file and prints it out
date > file - Redirects datastream from standard output to file
ls -l /usr/bin > list.txt - Redirects output from ls command to file
sort -k5n list.txt > sorted_list.txt - Sorts a list and outputs it to a file
sorted_list.txt
Please note that with the redirection command >, you will basically always
replace the file. If you instead want to append, use >> instead.
cat < file - Redirects the contents of file to the cat command
cat < original.txt > output.txt - Write contents of original.txt to cat and
then write cat output to output.txt
cat nonexistentfile 2> errorlog.txt - Redirects output from standard error to
file errorlog.txt
cat nonexistentfile 2>> errorlog.txt - Redirects output from standard error
to append file errorlog.txt
1> - Redirection of standard output - Can also use only >.
2> - Redirection of standard error
cat bees.txt ants.txt > insects.txt 2> error.txt - Redirect to insects.txt
and if error, to error.txt
ls docs > output.txt 2> output.txt - Datastream to both output.txt and if
error, also output.txt
ls docs > output.txt 2>&1 - Same as above (shortcut)
ls docs &> output.txt - Same as above
command1 | command2 - Piping, take the output from command1 to input it to
the second command
ls -l /usr/bin/ | less - Scroll though the ls -l /usr/bin/ command.
ls /usr/bin/ -1 | wc -l - Counts the number of programs in /usr/bin/
ls /usr/bin/ -1a | wc -l - Same as above, except it does not account for the
. and .. commands
> - Connects a command to some file
| - Connects a command to another command
ls /usr/bin/ -1a | wc -l > somefile.txt - Redirects the output from the pipe
to somefile.txt
cat msg.txt | tr s S - Replaces s with S and writes it to standard output
cat msg.txt | tr s a - Replaces s with a in the file msg.txt and writes it
to standard output
cat msg.txt | tr a-z A-Z - Converts the text in cat.txt to upper case
letters.
cat data.txt | tr -d [:alpha:] Deletes any alphabetic characters in data.txt
and write it to standard output.
cat data.txt | tr -d [:alpha:] | tr -d : | tr -d [:blank:] - Removes
alphabetic characters, colons and blanks from data.txt and writes it to
standard outpujt
cat file | head -7 | tail -5 - Writes out the lines 3-7 to standard output
cat countries.txt gives following:
cat -n countries.txt | head -7 | tail -5 - Same as before but with numbering
of lines
ls -lh | sort -rhk 5 | head -3 - Displays the three largest files in the
current directory
du -ha /usr/bin/ | sort -h | tail -4 | head -3 - Same as above, excludes the directory itself
du -ha /usr/bin/ | sort -h | tee sizes.txt | tail -4 | head -3 - Saves the output from the command du -ha /usr/bin/ | sort -h into a file named sizes.txt and then prints the 3 largest file to standard output from the same command.
echo This folder containts the files * - Writes "This folder contains the files file1 file2 file3 ...", to standard output.
echo *.txt - Writes all filenames in folder, with prefix .txt, to standard output.
echo p* - Writes out all filenames in the current directory that starts with the character p.
ls -l *at* - Selects the output from the ls -l command that has the characters ´at´ in its filename and writes it to standard output.
* - Matches all characters
? - Matches only one character
ls picture?.png - Prints out all files e.g. picture1.png picture2.png ...
echo app[1-3].css - prints out app1.css, app2.cs app3.css if they exist in the working folder
echo [A-Z]* - echos all the filenames that starts with a character between A-Z
[] - Ranges
^ - Negating ranges
ls [^a]* - Will match any files that do not start with an "a".
ls [^0-9]* - Will match any files that do not start with a numeric digit (0-9)
echo [^Cc] - Echo all files in working directory that doesnt start with "c" or "C"
cd ~ - Changes working directory to home directory
{} - Brace expansion
touch pages{1,2,3}.txt - Will generate three files, pages1.txt, pages2.txt, pages3.txt
echo {Mon, Tue, Wed, Thu, Fri}_Planner.txt - Prints Mon_Planner.txt ... Fri_Planner.txt to standard_output.
touch {Mon, Tue, Wed, Thu, Fri}_Planner.txt - Creates following files.
echo {2..10..2} - Prints 2,4,6,8,10
mdkir journal_day{1..365} - Creates 365 directories called journal_day1 ... journal_day365
mkdir -p {Mon, Tue, Wed, Thu, Fri, Sat, Sun}/{Breakfast, Lunch, Dinner} - Creates folder structure Mon ... Sun with Breakfast ... Dinner as subfolders
echo {x,y{1..5},z} - prints x,y1,y2,y3,y4,y5,z to standard output
echo {Mon,Tue{1..10},Wed} - Prints Mon Tue1 Tue2 Tue3 Tue4 Tue5 Tue6 Tue7 Tue8 Tue9 Tue10 Wed
echo $((10 + 3)) - Gives output of 13
echo $((10 / 3)) - Gives 3
echo $((10 ** 3)) - Gives 10 to the power of 3
echo "Today is.... $(date)" - Today is... fre 21 maj 2021 21:02:01 CEST
echo 'Today is.... $(date)' - Today is... $(date)
echo Hello There $(whoami) - Hello There Mikael
echo Today is date - Today is Friday.....
locate filename - Search for the file filename on your linux machine
find -type f - Will limit the search for files
find -type d - Will limit the search to files
find ~/Desktop -name "*.txt" - Find files on the desktop with the filetype .txt
find ~ -iname "*chick*" - find files that contains chick in the filename.
find ~/Desktop -iname "*[0-9]*" - Find files with numbers in the filename in the home Desktop folder.
find -size +1G - Find files that are larger than 1 GB
find -size -50M - Find files that has a size less than 50MB
find -user mikael - Find all files that belongs to the user mikael
find -empty -type f - Find empty files on the system
mtime - Modification time, the time when the file content last changed
ctime - The time when a file was last changed. Same as mtime but also accounts for changes in the name of the file, the moving of files and altering of permissions
atime - Access time, updated when a file is read by an application or command like cat.
ls -lc - Show ls command with ctime
ls -l - Show ls command with mtime
ls -lu - Show ls command with atime
touch last_week.txt -d "1 week ago" - Creates a file with the mtime for 1 week ago
touch last_month.txt -d "1 month ago" - Creates a file with the mtime for 1 month ago
find -mmin 30 - Find files that were modified exactly 30 munutes ago
find -mmin +30 - Find files that were modified mote than 30 minutes ago
find -mmin -30 - Find files that were modified less than 30 minutes ago
find -amin +100 - Find all that were accessed more than 100 minutes ago
find -mtime -5 - Find all files that were created less 5 days ago
find -name "*chick*" -or -name "*kitty*" - Find files that has chick or kitty in the filename
find -type -f -not -name "*.html" - Find files but ignore html files
find ~ -iname "tue*" -or -iname "mon*" - Find files in homedirectory that starts with tue or mon (case insensitive).
find ~ -type f -empty -exec ls -l '{}' ';' - Find all files in home directory that are empty and show the information that the command ls -l provides
find -name "*broken*" -exec rm '{}' ';' - Find all files that contains broken in the filename (case sensitive) and remove them
find -name "*broken*" -ok rm '{}' ';' - Find all files that contains broken in the filename (case sensitive) and promt removal of each file (asks for permission)
find -empty -ok rm '{}' ';' - Finds empty files in the current working directory and promt for permission about approval
find -type f -name "*.html" - exec cp '{}' '{}_COPY' ';' - Find html files in the current working directory and copy each file to a file with the same filename with the extension _COPY