Learn How to Use Linux, Linux Mint Cinnamon 20 Bootable 8GB USB Flash Drive - Includes Boot Repair and Install Guide 
I have only recently begun memorizing useful Linux terminal (command line) codes. Instead of keeping my list of useful terminal codes in Google Drive, I decided to share them with you.
Batch Replacing Text in Multiple Files
Some of these include recursive text replacement in subdirectories. I'm only researching this right now and this is not tested. I am not responsible for damage to your computer or loss of files
The example below uses grep to recursively find files.
grep -rli 'old-word' * | xargs -i@ sed -i 's/old-word/new-word/g' @
Command breakdown
grep -r: --recursive, recursively read all files under each directory.
grep -l: --print-with-matches, prints the name of each file that has a match, instead of printing matching lines.
grep -i: --ignore-case.
xargs: transform the STDIN to arguments, follow this answer.
xargs -i@ ~command contains @~: a placeholder for the argument to be used in a specific position in the ~command~, the @ sign is a placeholder which could replaced by any string.
sed -i: edit files in place, without backups.
sed s/regexp/replacement/: substitute string matching regexp with replacement.
sed s/regexp/replacement/g: global, make the substitution for each match instead of only the first match.
This is the bash script I ended up using
It's a mess but it worked
l#!/bin/bash
SRC='$url="https://blah"';
DST='$url="https:/foo"';
find . -type f -name "*.*" -exec sed -i 's,'"$SRC"','"$DST"',' {} ;
find . -type f -exec sed -i 's+https://InHomeComputerHelp.com+https://InHomeComputerHelp.com+g' {} +
find . -type f -exec sed -i 's+https://mobilecomputersupportoahu.com+https://InHomeComputerHelp.com+g' {}
Updating Linux Mint
sudo apt update && sudo apt upgrade -y
Installing Brave Internet Browser On Linux Mint
sudo apt install apt-transport-https curl
sudo curl -fsSLo /usr/share/keyrings/brave-browser-archive-keyring.gpg https://brave-browser-apt-release.s3.brave.com/brave-browser-archive-keyring.gpg
echo "deb [signed-by=/usr/share/keyrings/brave-browser-archive-keyring.gpg arch=amd64] https://brave-browser-apt-release.s3.brave.com/ stable main"|sudo tee /etc/apt/sources.list.d/brave-browser-release.list
sudo apt update
sudo apt install brave-browser
I just memorized this code and wanted to share. This will make your htdoc folder for XAMPP writeable. I found this as I was working on my first computer-based local website.
sudo chmod 777 -R /opt/lampp/htdocs/
If you're having trouble getting Apache Web Server to start
sudo systemctl stop nginx
I don't remember where I saved these bash commands from. I've seen websites come and go so I tend to save things with copy and paste to my Google Drive. Don't worry though. I use this website for my in home computer, cell phone and tablet tutoring and troubleshooting business. So this website is here to stay. Bookmark it and check back often. Follow me on Twitter to subscribe.
An A-Z Index of the Bash command line for Linux.
alias Create an alias •
apropos Search Help manual pages (man -k)
apt-get Search for and install software packages (Debian/Ubuntu)
aptitude Search for and install software packages (Debian/Ubuntu)
aspell Spell Checker
awk Find and Replace text, database sort/validate/index
b
basename Strip directory and suffix from filenames
bash GNU Bourne-Again SHell
bc Arbitrary precision calculator language
bg Send to background
break Exit from a loop •
builtin Run a shell builtin
bzip2 Compress or decompress named file(s)
c
cal Display a calendar
case Conditionally perform a command
cat Concatenate and print (display) the content of files
cd Change Directory
cfdisk Partition table manipulator for Linux
chgrp Change group ownership
chmod Change access permissions
chown Change file owner and group
chroot Run a command with a different root directory
chkconfig System services (runlevel)
cksum Print CRC checksum and byte counts
clear Clear terminal screen
cmp Compare two files
comm Compare two sorted files line by line
command Run a command - ignoring shell functions •
continue Resume the next iteration of a loop •
cp Copy one or more files to another location
cron Daemon to execute scheduled commands
crontab Schedule a command to run at a later time
csplit Split a file into context-determined pieces
cut Divide a file into several parts
d
date Display or change the date & time
dc Desk Calculator
dd Convert and copy a file, write disk headers, boot records
ddrescue Data recovery tool
declare Declare variables and give them attributes •
df Display free disk space
diff Display the differences between two files
diff3 Show differences among three files
dig DNS lookup
dir Briefly list directory contents
dircolors Colour setup for `ls'
dirname Convert a full pathname to just a path
dirs Display list of remembered directories
dmesg Print kernel & driver messages
du Estimate file space usage
e
echo Display message on screen •
egrep Search file(s) for lines that match an extended expression
eject Eject removable media
enable Enable and disable builtin shell commands •
env Environment variables
ethtool Ethernet card settings
eval Evaluate several commands/arguments
exec Execute a command
exit Exit the shell
expect Automate arbitrary applications accessed over a terminal
expand Convert tabs to spaces
export Set an environment variable
expr Evaluate expressions
f
false Do nothing, unsuccessfully
fdformat Low-level format a floppy disk
fdisk Partition table manipulator for Linux
fg Send job to foreground
fgrep Search file(s) for lines that match a fixed string
file Determine file type
find Search for files that meet a desired criteria
fmt Reformat paragraph text
fold Wrap text to fit a specified width.
for Expand words, and execute commands
format Format disks or tapes
free Display memory usage
fsck File system consistency check and repair
ftp File Transfer Protocol
function Define Function Macros
fuser Identify/kill the process that is accessing a file
g
gawk Find and Replace text within file(s)
getopts Parse positional parameters
grep Search file(s) for lines that match a given pattern
groupadd Add a user security group
groupdel Delete a group
groupmod Modify a group
groups Print group names a user is in
gzip Compress or decompress named file(s)
h
hash Remember the full pathname of a name argument
head Output the first part of file(s)
help Display help for a built-in command •
history Command History
hostname Print or set system name
i
iconv Convert the character set of a file
id Print user and group id's
if Conditionally perform a command
ifconfig Configure a network interface
ifdown Stop a network interface
ifup Start a network interface up
import Capture an X server screen and save the image to file
install Copy files and set attributes
j
jobs List active jobs •
join Join lines on a common field
k
kill Kill a process by specifying its PID
killall Kill processes by name
l
less Display output one screen at a time
let Perform arithmetic on shell variables •
link Create a link to a file
ln Create a symbolic link to a file
local Create variables •
locate Find files
logname Print current login name
logout Exit a login shell •
look Display lines beginning with a given string
lpc Line printer control program
lpr Off line print
lprint Print a file
lprintd Abort a print job
lprintq List the print queue
lprm Remove jobs from the print queue
ls List information about file(s)
lsof List open files
m
make Recompile a group of programs
man Help manual
mkdir Create new folder(s)
mkfifo Make FIFOs (named pipes)
mkisofs Create an hybrid ISO9660/JOLIET/HFS filesystem
mknod Make block or character special files
more Display output one screen at a time
most Browse or page through a text file
mount Mount a file system
mtools Manipulate MS-DOS files
mtr Network diagnostics (traceroute/ping)
mv Move or rename files or directories
mmv Mass Move and rename (files)
n
netstat Networking information
nice Set the priority of a command or job
nl Number lines and write files
nohup Run a command immune to hangups
notify-send Send desktop notifications
nslookup Query Internet name servers interactively
o
open Open a file in its default application
op Operator access
p
passwd Modify a user password
paste Merge lines of files
pathchk Check file name portability
ping Test a network connection
pkill Kill processes by a full or partial name.
popd Restore the previous value of the current directory
pr Prepare files for printing
printcap Printer capability database
printenv Print environment variables
printf Format and print data •
ps Process status
pushd Save and then change the current directory
pv Monitor the progress of data through a pipe
pwd Print Working Directory
q
quota Display disk usage and limits
quotacheck Scan a file system for disk usage
quotactl Set disk quotas
r
ram ram disk device
rar Archive files with compression
rcp Copy files between two machines
read Read a line from standard input •
readarray Read from stdin into an array variable •
readonly Mark variables/functions as readonly
reboot Reboot the system
rename Rename files
renice Alter priority of running processes
remsync Synchronize remote files via email
return Exit a shell function
rev Reverse lines of a file
rm Remove files
rmdir Remove folder(s)
rsync Remote file copy (Synchronize file trees)
s
screen Multiplex terminal, run remote shells via ssh
scp Secure copy (remote file copy)
sdiff Merge two files interactively
sed Stream Editor
select Accept keyboard input
seq Print numeric sequences
set Manipulate shell variables and functions
sftp Secure File Transfer Program
shift Shift positional parameters
shopt Shell Options
shutdown Shutdown or restart linux
sleep Delay for a specified time
slocate Find files
sort Sort text files
source Run commands from a file '.'
split Split a file into fixed-size pieces
ssh Secure Shell client (remote login program)
stat Display file or file system status
strace Trace system calls and signals
su Substitute user identity
sudo Execute a command as another user
sum Print a checksum for a file
suspend Suspend execution of this shell •
sync Synchronize data on disk with memory
t
tail Output the last part of file
tar Store, list or extract files in an archive
tee Redirect output to multiple files
test Evaluate a conditional expression
time Measure Program running time
timeout Run a command with a time limit
times User and system times
touch Change file timestamps
top List processes running on the system
tput Set terminal-dependent capabilities, color, position
traceroute Trace Route to Host
trap Run a command when a signal is set(bourne)
tr Translate, squeeze, and/or delete characters
true Do nothing, successfully
tsort Topological sort
tty Print filename of terminal on stdin
type Describe a command •
u
ulimit Limit user resources •
umask Users file creation mask
umount Unmount a device
unalias Remove an alias •
uname Print system information
unexpand Convert spaces to tabs
uniq Uniquify files
units Convert units from one scale to another
unrar Extract files from a rar archive
unset Remove variable or function names
unshar Unpack shell archive scripts
until Execute commands (until error)
uptime Show uptime
useradd Create new user account
userdel Delete a user account
usermod Modify user account
users List users currently logged in
uuencode Encode a binary file
uudecode Decode a file created by uuencode
v
v Verbosely list directory contents (`ls -l -b')
vdir Verbosely list directory contents (`ls -l -b')
vi Text Editor
vmstat Report virtual memory statistics
w
wait Wait for a process to complete •
watch Execute/display a program periodically
wc Print byte, word, and line counts
whereis Search the user's $path, man pages and source files for a program
which Search the user's $path for a program file
while Execute commands
who Print all usernames currently logged in
whoami Print the current user id and name (`id -un')
wget Retrieve web pages or files via HTTP, HTTPS or FTP
write Send a message to another user
x
xargs Execute utility, passing constructed argument list(s)
xdg-open Open a file or URL in the user's preferred application.
yes Print a string until interrupted
zip Package and compress (archive) files.
. Run a command script in the current shell
!! Run the last command again
### Comment / Remark
Commands marked • are bash built-ins
Many commands particularly the Core Utils are also available under alternate shells (C shell, Korn shell etc).
