# cheat_sheet.org.sh
# (C) William Hackmore, 2010
# The contents of this file are released under the GNU General Public
# License. Feel free to reuse the contents of this work, as long as the
# resultant works give proper attribution and are made publicly available
# under the GNU General Public License.
# Best viewed in emacs org-mode.

* Reference:
** Basics:
*** Getting help:

# View the manual for target command
man command

# Get help with a target command (probably the same as above, but not always):
command -h

# In case you forget the name of a command, print possible commands relating to guess:
apropos guess

# View index of help pages:
info

*** Command Line Utilities:
**** Basic File and Directory Operations:
# Print current working directory:
pwd

# Show files in current directory:
ls

# Show maximum information about all files, including hidden:
ls -a

# Recurse into subdirectories and list those as well:
ls -R

# Move/rename a file or directory (be careful that you don't move the source over a destination with the same name):
mv source destination

# Delete target forever (be very careful), use -r recursive flag for directories:
rm target

# Copy file or directory:
cp source destination

# Mount filesytem:
mount /dev/device_name /media/device_name

# Unmount:
umount /media/device name

# Forensically clone filesystems and do other low-level operations on files. Be careful with this one. Can be destructive:
dd

# Work with filesystems and partitions. (Easier, still quite dangerous):
fdisk

**** System Administration:

# Execute command as an administrator (can be destructive/insecure. Use only for system administration tasks):
sudo command

# Become system administrator:
sudo -s

# Quit system administration:
exit

***** Installing software from a .tgz (also known as a tarball):

# First, unzip the tarball (see section on tar, below)
# Next, move into unzipped directory:
cd software_directory

# Always read README first if it is provided, in case there are any modifications to the procedure outlined below:
cat README

# Automatically check for appropriate configurations and generate a MAKE file in the directory:
./configure

# Compile software. May require sudo:
make

# Move files into their appropriate locations. May also require sudo:
make install

# Clean up files in directory, in case make command fails, or just to remove unnecessary cruft:
make clean

***** Ubuntu/Debian Software repositories:

# Check distro repositories for software updates:
sudo apt-get update

# Download and install updates (update first):
sudo apt-get upgrade

# Search for package in the repositories:
apt-cache search keyword

# Get more detail on one specific package:
apt-cache show package_name

# Download and install a package:
sudo apt-get install package_name


***** Redhat/Fedora Software repositories:
***** Added: 2013/03/09: Fr. Visminlu Vicente L. Chua, S.J.

# Check distro repositories for software updates:
yum check-update

# Download and install updates (update first):
yum update

# Search for package in the repositories:
yum search keyword

# Get more detail on one specific package:
yum info package_name

# Download and install a package:
yum install package_name



# View the output of a command in a more convenient format:
command | less

**** Working With Files:

# Print a file in terminal:
cat file

# Find files matching filename:
locate filename

# Search through filename for matches to phrase:
grep phrase filename

# Search through output of a command for phrase:
command | grep phrase

**** Working With Processes:

# List all running processes:
ps -e

# Standard system monitor showing a more extensive view of all processes and system resources:
top

# Like top, but with a better, cleaner interface:
htop

# Stop a process from using all system resources and lagging computer:
renice process_name

# Kill misbehaving process (use sparingly, last resort, try 'nice' command first):
pkill process name

# Start a process in the background
command &

# Start a process in the background and have it keep running after you log off
nohup command &

**** Compression and Encryption:

# Make a simple compressed backup of a file or directory:
tar -cvzf backup_output.tgz target_file_or_directory

# Open a compressed .tgz or .tar.gz file:
tar -xvf target.tgz

# Encrypt a file:
gpg -o outputfilename.gpg -c target_file

# Decrypt a file:
gpg -o outputfilename -d target.gpg

# Zip and encrypt a directory simultaneously:
gpg-zip -o encrypted_filename.tgz.gpg -c -s file_to_be_encrypted

*** The Bash shell:
**** File Name expansions:
# Current user's home directory:
~/

# Current directory:
./

# Parent directory:
../

# Or even (Two parent directories down):
../../

# All files in target directory. (Be very careful.):
/*

**** Output Redirects:

# Redirect output of one command into the input of another with a pipe:
command_1 | command_2

# Or even:

command_1 | command_2 | command_3

# Redirect output to a file:
command > file

# Or:

file > file

# Or even, to redirect in a different direction:
file < file

# Append output rather than writing over the target file:

file_or_command >> file

# Works like |, but it writes output to both target and terminal:
tee target

# Redirect standard output and error to /dev/null, where it is deleted.
command > /dev/null 2>&1

**** Controlling Execution:
# Wait until command 1 is finished to execute command 2
command_1 ; command_2

# Or even:
command_1 ; command_2 ; command_3

# && acts like ; but only executes command_2 if command_1 indicates that it succeeded without error by returning 0.
command_1 && command_2

# || acts like && but only executes command_2 if command_1 indicates an error by returning 1.
command_1 || command_2

**** Bash Wildcards:
# Zero or more characters:
*

# Matches "phrase" and any number of trailing characters:
phrase*

# Matches any incidences of "phrase" with any trailing or leading chars:
*phrase*

# Matches any one char:
?

# Matches any of the characters listed inside brackets:
[chars]

# Matches a range of chars between a-z:
[a-z]

** Advanced:
*** Command Line Utilities, Continued:
**** Networking:

# Configure network interfaces:
ifconfig

# Configure wireless network interfaces:
iwconfig

# Connect to a remote server.
ssh username@ip_address

# Forward X from target to current machine (Get a remote desktop. Somewhat obscure, but very useful):
ssh -X username@ip_address

# Copy files over the network from one machine to another:
scp source_filename:username@ip_address target_filename:target_username@target_ip_address

# Copy only changes between files or directories (super efficient way to sync directories, works either locally or with remote servers using username@ip_address:optionalport, just like ssh):
rsync source target

# Check to see if target is online and responding
ping ip_address

# View network route to target:
traceroute6 ip_address
# Added: 2013/03/16: Fr. Visminlu Vicente L. Chua, S.J. : for IPv4
traceroute ip_address

# Network Monitor
netstat

# Manage standard linux firewall (advanced users only)
iptables

# Scan this machine to check for open ports:
nmap 127.0.0.1

***** netcat:

# Listen for input from network on recieving_port, dump it to a file (insecure, but handy):
netcat -l recieving_port > file_copied

# Pipe the output of a command to a target ip and port over the network:
command | netcat -w number_of_seconds_before_timeout target_ip target_port

# Use tar to compress and output a file as a stream, pipe it to a target ip and port over the network:
sudo tar -czf - filename | netcat -w number_of_seconds_before_timeout target_ip target_port

**** Users and Groups:
# Change owner of a file or directory:
chown user_name:group_name directory_name

# Change privileges over file or directory (see man page for details.)
chmod

# Create a new user:
adduser

# Change user privileges (be very careful with this one):
usermod

# Delete user
deluser

# Print groups:
groups

# Create a new group:
groupadd

# Change group privileges:
groupmod

# Delete group:
delgroup

# Temporarily become a different user:
su username

# Print usernames of logged in users:
users

# Write one line to another user from your terminal:
talk

# Interactive talk program to talk to other users from terminal (must be installed from repositories.):
ytalk

**** Working With Files, Continued:
# View what processes are using what files:
lsof

# View the differences between two files:
diff file_1 file_2

# Output the top number_of_lines of file:
head -n number_of_lines file

# Like head, but it outputs the last -n lines:
tail -n number_of_lines file

# Checksum a file:
md5sum file

# Checksum every file in a directory (install this one from repositories.):
md5deep directory

# Checksum a file (better algorithm with no hash collisions):
sha1sum

# Same operation as md5deep, but using sha1:
sha1deep

# Call command every few number_of_seconds, and display output:
watch -n number_of_seconds command

# Execute command, print how long it took:
time command

# View files in directory from largest to smallest:
du -a directory | sort -n -r | less

# remove spaces from filenames in current directory:
rename -n 's/[\s]/''/g' *

# change capitals to lowercase in filenames in current directory:
rename 'y/A-Z/a-z/' *

***** Environment and Hardware:
# Print full date and time:
date

# Print the hostname of this machine:
echo $HOSTNAME

# Print information about current linux distro:
lsb_release -a

# Print linux kernel version:
uname -a

# Print information about kernel modules:
lsmod

# Configure kernel modules (never do this ;p ):
modprobe

# View Installed packages:
dpkg --get-selections

# View Installed packages (Red Hat/Fedora):
# Added: 2013/03/15: Fr. Visminlu Vicente L. Chua, S.J.
rpm -qa

# Print environment variables:
printenv

# List hardware connected via PCI ports:
lspci

# List hardware connected via USB ports:
lsusb

# Print hardware info stored in BIOS:
sudo dmidecode

# Dump captured data off of wireless card:
dumpcap

# Dump info about keyboard drivers:
dumpkeys

***** Ubuntu System Administration, Advanced (Continued):

# Add a Personal Package Archive from Ubuntu Launchpad:
add-apt-repository

# Install a .deb file from command line:
sudo dpkg -i package.deb

# Install an .rpm file from command line:
# Added: 2013/03/09: Fr. Visminlu Vicente L. Chua, S.J.
yum install package.rpm

**** Python:

# Update pip (Python package manager):
pip install -U pip

# search pip repos for a library:
pip search library_name

# create a virtual python environment to allow install of many different versions of the same Python modules:
virtualenv dirname --no-site-packages

# connect to a virtual python environment
source dirname/bin/activate

# disconnect from a virtual python environment:
deactivate

# install package into virtual python environment from outside:
pip install packagename==version_number -E dirname

# export python virtual environment into a shareable format:
pip freeze -E dirname > requirements.txt

# import python virtual environment from a requirements.txt file:
pip install -E dirname -r requirements.txt

**** git (all commands must be performed in the same directory as .git folder):

# Start a new git project:
git init

git config user.name "user_name"

git config user.email "email"

# Make a copy of a git (target can be specified either locally or remotely, via any number of protocols):
git clone target

# Commit changes to a git:
git commit -m "message"

# Get info on current repository:
git status

# Show change log for current repository:
git log

# Update git directory from another repository:
git pull [target]

# Push branch to other repository:
git push [target]

# Create a new branch:
git branch [branchname]

# Switch to target branch:
git checkout [branchname]

# Delete a branch:
git branch -d [branchname]

# Merge two branches:
git merge [branchname] [branchname]

# Show all branches of a project:
git show-branch

*** Virtualization:

#clone a virtual machine (this works, it's been tested):
vboxmanage clonehd virtual_machine_name.vdi --format VDI ~/target_virtual_machine_name.vdi

#mount a shared virtual folder:
#you need to make sure you have the right kernel modules. You can do this with modprobe, but this package works instead in a ubuntu-specific way.

sudo apt-get install virtualbox-ose-guest-utils

sudo mount -t vboxsf name_of_shared_folder_specified_in_Virtualbox path_of_mountpoint

*** mysql:

# Get help:
help

# Show databases:
show databases;

# Choose a database to use:
use database_name_here;

# Show database schema:
show tables;

# Delete database:
DROP DATABASE databasename;

# New database:
CREATE DATABASE databasename;

# Create a new user:
CREATE USER username@localhost IDENTIFIED BY 'password';

# Show users:
select * from mysql.user;

# Delete a user:
delete from mysql.user WHERE User='user_name';

# Give user access to all tables (make them root). the "%" means that they can sign in remotely, from any machine, not just localhost.:
grant all privileges on *.* to someusr@"%" identified by 'password';

# give certain privileges to a user on a certain database:
grant select,insert,update,delete,create,drop on somedb.* to someusr@"%" identified by 'password';

# Tell mysql to use new user priv policies:
flush privileges;

# change user password:
use mysql;

update user set password='password'('newpassword') where User='user_name';

# mysql command line args:
# export text file with commands to rebuild all mysql tables:
mysqldump databasename > dumpfilename.txt

# restore from a dump:
mysql -u username -p < dumpfilename.txt

# dump entire database:
mysqldump -u username -p --opt databasename > dumpfile.sql

# restore from entire database dump:
mysql -u username -p --database=databasename < dumpfile.sql