​​[username]$  

# Print username
whoami

# What time/date is it?
date

# Where in the computers files am I? 
# print working directory (the folder you a currently in)
pwd

# What kind of Unix shell am I using? (Bash is most common)
# echo is the command to print something on the commnad line.
# In this instance we print the default Unix variable SHELL and
# the $ and {} brackets are used to call a Unix variable
echo ${SHELL}

# We can create our own Unix variables using these commands, 
# but we need to use backtick `` to substitute in the date command
# as the variable learning_unix_since .
# Also, notice no spaces around = 
# this ensure it will be read as a unix variable
learning_unix_since=`date`
echo ${learning_unix_since}

# Use the up arrow ↑ on your keyboard to cycle back through the
# commands used so far (really useful to go back and try again 
# when something doesn't work)

# Show the contents of a directory
ls

# Show the contents of a directory with details
ls -l

# See the contents of a subfolder 
# (the TAB key autofills, and is an essential tool!)
ls <subfolder>/

# Make a new folder with the mkdir command called: unix_workshop
mkdir <name>

# Change directory to specified pathway
cd <pathway>

# touch is a command that can be used to create files 
# if they don't already exist in the directory. 
# In the directory we just made unix_workshop, 
# create a text file using touch.
touch random_file_00.txt

# Change directory, up one in the pathway.
cd ../

# Wildcards 
* # one or more of any character
# Example use of * (list all files ending in .txt)
ls *.txt

# Make a copy of a file 
cp <existing filename> <destination path/filename>

# Move file, but also used for renaming
mv <filename> <destination>

# Remove a file; 
# use with caution
# use with caution
# use with caution
# use with caution
# use with caution
# use with caution
# use with caution
# there's no going back, it's gone forever!
rm <filename>

# Remove a directory;
# can only remove an empty directory
rmdir <name>

# Move to a directory with many different file types
# Get the line, word, character count of a file
wc <filename>

# Get just the line count
wc -l <filename>

# Pipe command; join commands together
# The pipe key is near Enter, 
# Shift+| (on US-keyboard) 
|

# E.g. count of items in the directory
ls <directory> | wc - l

# Get number of txt files in a directory
ls *.txt | wc -l

# Make a file with the output of a command using >
# will overwrite existing file
ls > <filename>

# Global regular expression
# searches for a string in a file
# good for quickly searching through 
# scripts to re-use bits of code
grep <"string"> <file>

# finding a file in your directory tree
find -name "<filename>"

# get help for any command 
<command> --help

# cancel incomplete command
CTRL + C

# Viewing the head (start) or tail (end) files
head <filename>
tail <filename>

# Let's be more specific about looking at the head of a file
head -n <no. rows> <filename>

# Open vi, a text editor (can use another text editor)
# this will create a file if it doesn't exist
vi <filename>

# To edit the file, go to EDIT mode by
# pressing Insert key, should see INSERT on the 
# bottom bar
Ins

# To go back to COMMAND mode, press Esc key
# bottom bar should go blank
Esc

# Exit vi, and save changes: in COMMAND mode
:wq

# Exit vi, without saving: in COMMAND mode
:q!

# create some files to eventually change the name of
touch random_file_{01..99}.txt

# the {01..99} creates a sequence from 1 to 99, try it after
# the  echo command.
# We should have just created 99 files empty text files, 
# using this sequence.

# We can use vi to create the script
vi <filename>.sh 

#!/bin/bash
# This first line ensures that your Unix shell knows 
# this is a bash shell script (not another shell type) 
# and can interpret it accordingly 

# First we set the pathway to the files wanting to be renamed
# we can use the present working directory
path_to_files=`pwd`

# Start a loop that looks for .txt files in the directory ${path_to_files}
# then loop over each file in that directory.
for file in ${path_to_files}/*.txt
do
  # Take the extension off the filename using % 
  # the % sign cuts a string of characters, like the filename
  # file in this instance
  prefix=${file%.txt}
  
  # use the prefix to create the new name for the file, 
  # by adding _modified to each filename
  outfile=${prefix}_modified.txt
  
  # print out the filename, the prefix and the new filename
  echo ${file} ${outfile}

  # perform the name change using the mv command, 
  # and the variable we just set up outfile
  # mv <filename> <new filename>
  mv ${file} ${outfile}
done

# to execute the shell script we just made
bash <filename>.sh

# see all commands since the start of the session
history

# save history to a text file
history > tutorial_history.txt

# clear your shell screen of previous commands
clear