DQ - BASH Flashcards
Listing the non-hidden contents of the current directory without any options
ls
Listing the non-hidden contents of path /home/dq
ls /home/dq
Listing the non-hidden contents of the current directory in long format
ls -l
Listing all contents of the current directory
ls -a
Listing all contents of /home/dq in long format, except for the directories . and ..
ls -Al
Change to directory /filename
cd /filename
Change to the parent directory of the current directory
cd ..
Change to the parent directory of the parent directory of the current directory
cd ../..
Change to your home directory
cd
OR
cd ~
Change to the home directory of user dq
cd ~dq
Change to the previous directory
cd -
Creating a directory called my_dir
mkdir my_dir
Deleting an empty directory called my_dir
rmdir my_dir
Interactively creating a copy of file my_file1 as my_file2
cp -i my_file1 my_file2
Create a copy of directory my_dir1 as my_dir2
cp -R my_dir1 my_dir2
Deleting file my_file
rm my_file
Deleting the non-empty directory my_dir
rm -R my_dir
Moving my_file to my_dir
mv my_file my_dir
Renaming my_file as our_file
mv my_file our_file
Wildcard to match any single character
?
Wildcard to match any multitude of string characters
*
Wildcard to match k,3, z, or J
[k3zJ]
Wildcard matching any character NOT in k,3, z, or J
[!k3zJ]
Wildcard for letters (case insensitive)
[[:alpha:]]
Wildcard for numbers
[[:digit:]]
Wildcard for letters or numbers
[[:alnum:]]
Wildcard for lowercase letter
[[:lower:]]
Wildcard for uppercase letter
[[:upper:]]
All files whose name is three characters long
???
All files ending with .tsv
*.tsv
All files starting with the first 2 decades of this century, followed by an underscore
20[01][[:digit:]]_*
All files starting with either a lowercase letter or zero, followed by a question mark and ending in .txt
[[:lower:]0]\?*.txt
Identify current user
whoami
Identify user id, group id, and groups for a user
id
Identify all groups for a user
group
See file’s metadata
stat file
Adding execution permission to the owner on file
chmod u+x file
Removing writing permission to the primary group on file
chmod g-w file
Setting read and execution permissions to others on file
chmod o=rx file
Add write permissions to owner, remove execute from primary group, and set others to read only
chmod u+w,g-x,o=r file
Octal notation for permissions
R W X
4 2 1
Changing both the ownership and the group of file1 to new_owner and new_group
sudo chown new_owner:new_group file1
Changing the ownership of file while maintaining its group
sudo chown new_owner file
Changing the group of file while maintaining its ownership
sudo chown :new_group file
Run a command with superuser privileges
sudo command
Identify the type of a command
type command
Create an alias for the “date” command as d
alias d=date
Remove the alias named d
unalias d
Get a brief description of what an executable file does
whatis command
Access the manual of an executable file
man command
Access the manual of a built-in command
help command
See the contents of a file with less
less filename
See the contents of a file with less without wrapipng lines
less -S filename
What are the five different types of commands?
file builtin alias function keyword
(Only the executable files and built-ins have documentation)
Seeing the first 15 rows of filename
head -n 15 filename
Seeing the last 15 rows of filename
tail -n 15 filename
Counting number of lines, words, and characters in filename
wc filename
Pretty printing a CSV file:
column -s”,” -t filename
Extract a random sample of five rows from filename
shuf -n 5 filename
Determining the type of filename
type filename
Concatenate files together
cat file1 file2
Concatenate files together in revers order will preserving line order
tac file1 file2
Concatenate csv files together and then sort by the following in order:
Column 1 lexicographical order ascending
Column 3 numerical order descending
Columns 5 through 7 as one field
sort -t”,” -k1,1 -k3,3gr -k5-7 file1 file2
Remove duplicate lines from a file
sort -u filename
Selecting columns 2 , 3 and 7 through 9 on filename with : as a separator
cut -d”:” -f2,3,7-9
Print the lines of a file that does not match a regex pastern. Include the line number and make the search case-insensitive, and exclude the filename prefix
grep -vnih ‘RegEx_Patern’ filename
See all the lines of a file except for the first row
tail -n+2
Simply pring to screen “Hello, world!”
echo “Hello, world!”
Create empty files
touch file1 file2
Overwrite a file by redirecting the output of a command
cmd >filename
Append a file with the output of a command
cmd»_space;filename
Pipe the output of a command to the input of another command
cmd1 | cmd2
Discard the output of a command
cmd >/dev/null
Redirect stdout to a file
cmd >filename
--OR--
cmd 1>filename
Redirecting stdout and stderr to out and err respectively
cmd >out 2>err
Redirecting stdout and stderr to all_output
cmd >all_output 2>&1
Redirecting stdin from the shell to a file named input_file
cmd
