Basics
Showing & Navigating
Copying/Moving/Removing
Input & Output Redirects
Sorting & Filtering
Environment
clear: clears the terminal
nano <filename>: opens the nano text editor for specific file (optional)
^ –– in nano stands for ctrl
~ –– usually represents the users home directory
ls: lists all files (folders are called directories. files and directories are structured in a file system)
ls -a: lists all files + hidden files (-a is called an option)
ls -t: orders by time last added
ls -l: with long description (access-rights, n# of hard links, owner, group-name, size in bytes, date-last-modified, name)
ls -alt: -a, -t & -l together
pwd: print working directory path (the directory you’re currently in)
cd <directory-path>: change directory
cd folder/childfolder: two down
cd ..: one up
mkdir <name>: make directory
touch <name>: creates a new file inside the working directory
cat <filename>: outputs the content of a file to the console
wc <filename>: outputs the number of lines, words, and characters in file
cp <file-to-copy> <place-to-paste>: copies files and paste them somewhere else
cp <file1> <file2> <file3> <place-to-paste>: you can copy multiple files at once
cp _ <place-to-paste>: copy all files from working directory (special characters like _ are called wildcard, when you combine it with .txt for example would mean any file that ends with .txt)
scp <file-to-copy> <user>@<host-url>:<place-to-paste>: copies local files to a remote host location
scp ./*.txt root@157.97.110.218:/root/myTextFiles: will copy all files ending with txt inside the current working directory to the /root/myTextFiles on some remote host.
mv <file-to-move> <place-to-move>: moves a file
mv <file-to-rename> <new-filename>: renames a file
rm <file-to-remove>: removes a file or directory !permanently!
rm -r <dir-to-remove>: removes a dir and all its children !permanently!
echo "Hello" > world.txt: > redirects the standard output (Hello) into something else (world.txt)
cat file1.txt > file2.txt: content of file1 is redirected into file2 which overrides the content of file2 by the content of file1
cat file1.txt >> file2.txt: >> appends the output of file1 to file2
cat < file.txt: takes the output from the right and inputs it into the left
cat file.txt | wc: | is a "pipe". The | takes the standard output of the command on the left, and pipes it as standard input to the command on the right. You can think of this as "command to command" redirection.
cat text1.txt | wc | cat > text2.txt: multiple pipes can be combined here the output of text1.txt is given to wc whose output is given to cat which places it into text.txt
sort <filename>: outputs the sorted content of the file
cat <filename> | sort > <name-of-sorted-file>: outputs the content of filename binds it to the sort function that then redirect that sorted output into a file
uniq <filename>: filters out adjacent, duplicate lines in a file
sort <file> | uniq > <another-file>: sorts a file "pipes" (|) the sorted content to uniq which filters out all adjacent duplicates and gives the result back to another file
sort <file> | uniq -c > <another-file>: counting the duplicated lines in file
sort <file> | uniq -c | sort -nr > <another-file>: counting the duplicated lines in file and sort it (by frequency)
grep <keyword> <filename>: searches a file for lines that have the keyword and output the result (it is case sensitive)
grep -i <keyword> <filename>: here grep is case insensitive
grep -R <keyword> <folder>: searches all files in a directory and outputs filenames and lines containing matched results
grep -Rl <keyword> <folder>: searches all files in a directory and outputs only filenames with matched results
sed 's/<keyword>/<replacement>' <filename>: find in file and replace s = substitution. So sed 's/find/replace' in_this_file (only replace the first finding)
sed 's/<keyword>/<replacement>/g' <filename>: same as above but replaces all instances not only the first finding
sed 's/$/<addition>/' <filename>: adds something at the end of each line ($ matches the end of the string or line)
sed 's/^/<addition>/' <filename>: adds something at the beginning of each line (^ matches the beginning of the string or line)
nano ~/.bash_profile: creates a file to store environment settings. Whenever a session starts it will load it's content.
(within bash_profile) alias pd="pwd": create keyboard shortcuts, for commonly used commands.
(within bash_profile) export USER="username": create a variable that can be accessed by $USER
(within bash_profile) export PS1=">> ": to change the command prompt from $ to >>
source ~/.bash_profile: makes changes available without the fuzz to open a new console.
env: return a list of environment variables