The bare essentials to shell navigation

bash-survival-guide.sh

# I have forked a much more complete cheat sheet, but is complete at the expense of being accessable
# You can find that  bigger cheat sheet here https://gist.github.com/fathergoose/3fbc3b5f6c0ba3cbe367b18030b39aba
# things in <angleBrackts> are variables to be replaced for a spcific instance of the command

# Getting Help
man <command>               # Read the man(ual) page entry for a given command (detailed help)
<command> --help            # This *usually* prints a short summary of a command's options and arguments


# Directories 
pwd                          # tells you where you currently are
cd                           # changes to home
cd <dirname>                 # changes directory dirname
mkdir <dirname>              # make a new directory


# Files
ls                            # lists your files
ls -l                         # lists your files in 'long format', which contains the exact size of the file, who owns the file and who has the right to look at it, and when it was last modified
ls -a                         # lists all files, including hidden files
ln -s <filename> <link>       # creates symbolic link to file
touch <filename>              # creates or updates timestamp on file
cat <filename>                # output the contents of filename
mv <filename1> <filename2>    # moves a file
cp <filename1> <filename2>    # copies a file
rm <filename>                 # removes a file
chmod -options <filename>     # lets you change the read, write, and execute permissions on your files
grep <pattern> <filenames>    # looks for the string in the files
grep -r <pattern> <dir>       # search recursively for pattern in directory
less <filename>               # page though a file (read-only)
<command> | less              # page though the standard output
nano <filename>               # edit or create file; very simple and striaght-forward editor
vi <filename>                 # edit or create file; very confusing and life-changingly powerful editor


# Redirection
cmd1|cmd2                     # pipe; takes standard output of cmd1 as standard input to cmd2
> file                        # directs standard output to file
< file                        # takes standard input from file
>> file                       # directs standard output to file; append to file if it already exists
<> file                       # uses file as both standard input and standard output


# Know your shell
which <command>               # show the location of comamnd being envoked
env                           # show list of all environment variables
varname=value                 # defines a variable
export VARIABLE=<value>       # assign an environment variable (available to subprocesses)
echo $VARIABLE                # show the value of VARIABLE
alias ls="ls -la"             # assign `ls` to run `ls -la` everytime it is called
source <file>                 # read and execute contents of file as a bash script

# The default order for command lookup is functions, followed by built-ins, with scripts and executables last.
# There are three built-ins that you can use to override this order: `command`, `builtin` and `enable`.
command                       # removes alias and function lookup. Only built-ins and commands found in the search path are executed
builtin                       # looks up only built-in commands, ignoring functions and commands found in PATH
enable                        # enables and disables shell built-ins


# Shortcuts
# Many more than listed
CTRL+A                        # move to beginning of line
CTRL+B                        # moves backward one character
CTRL+C                        # halts the current command
CTRL+D                        # deletes one character backward or logs out of current session, similar to exit
CTRL+E                        # moves to end of line
CTRL+F                        # moves forward one character
CTRL+K                        # deletes (kill) forward to end of line
CTRL+U                        # kills backward from point to the beginning of line
CTRL+L                        # clears screen and redisplay the line
CTRL+Z                        # stops the current command, resume with fg in the foreground or bg in the background

# History
history                       # shows a list of previously run commands
!!                            # execute the last command
!n                            # execute command number n (numbers found in history command)
CTRL+N                        # next line in command history
CTRL+O                        # same as RETURN, then displays next line in history file
CTRL+P                        # previous line in command history
CTRL+R                        # searches backward

# SSH, System Processes & Network Commands
ssh user@host                 # connects to host as user
ssh -p <port> user@host       # connects to host on specified port as user
ssh-copy-id user@host         # adds your ssh key to host for user to enable a keyed or passwordless login

ifconfig                      # display network configuration information (like what your ip address is)
ping <host>                   # pings host and outputs results
wget <file>                   # downloads file, can be a web address like https://somesite.com/somefile.pdf

ps -u yourusername            # lists your processes
ps -axu                       # list all processes and owners
kill <PID>                    # kills (ends) the processes with the ID you gave
killall <processname>         # kill all processes with the name
top                           # displays your currently active processes