linux notes

/var/log/ (location of log files)
$USER (USER envrioment variable)


rm -r (remove directory and subs recursivley ad f to not promt)
mv (move\rename a file)

sudo adduser user --encrypt-home 

chmod 1777 (make directory with full access for your own files not others)
chown newUser file
chown :newGroup filels

awk -F":" '{ print "username: " $1 "\t\tuid:" $3 }' /etc/passwd 
	(list all users in system)

service ssh restart (restart ssh)

usermod -a -G group user (add group to particlar user, the -a appends)
groups user (show the groups the user is in)


sudo netstat -tanp (look for user sessions)
sudo kill -15 <process> (kill the ssh process)

vim commands:
v (start highlighting)
d (cut)
P (paste)


using screen:
Ctrl a d (detach)
screen -ls (list screens)
screen -r [particularSCreen] (reatttach a detached screen)

upstart log directory: 
/var/log/upstart/your-service-name.log.

exec start-stop-daemon --start --chuid gandalf --chdir /home/gandalf/server/ --exec /home/gandalf/server/startServer.sh

start-stop-daemon --start --chuid gandalf --exec /home/gandalf/server/startServer.sh

cd $ echo $PATH

/bin (common ternminal commands)
/boot (start up stuff, kernel and boot loader config files)
/dev (all device files, refer to actual devies)
/home (for users home directories)
/media (mount point for external media devices)
/mnt (also mount point but more for things lik network drives)
/opt (stores additonal software not handled by pakage managers)
/proc (virtual filesystem, mechanism for kenrel to send info to processes)
/root (super users home directory for when home is not available on boot)
/sbin (contains super user commands)
/srv (can contain data directories of services such as http)
/tmp (place for temporary files)
/usr (contains user utilites and replicates some root dir structures)
/var (for variable data that changes rapidly such as logs)
/lost+found (place where system puts things like corrupted files)
/run (?? something to do with running processes?)


mail -s "The subject goes here" jdoe 
 (send mail to another useremust have mailutils installed)
mail (check mail)


sudo ufw enable (enable firewall)
sudo ufw allow <port> 
	//add /tcp to make it exclusive to tcp
sudo ufw remove <rule> // remove a rule



//github configuration 
git config --global user.name "Your Name"
git config --global user.email youremail@example.com


//getting updates
sudo apt-get update        # Fetches the list of available updates
sudo apt-get dist-upgrade  # Installs updates

//mongodb important dirs and useful stuff
/var/log/mongodbd
/var/lib/mongodb (current location of dbs)
ps -ef | grep mongo

..repair bad mongo shutdown..
Do this... 
sudo rm /var/log/mongodbd/mongod.lock
Then restart....
To be more legit try this before you restart...
sudo mongod --dbpath /var/log/mongodbd --repair


//shutdown the system
sudo shutdown -h now

//changing evnviroment varialbes
export ENV_VAR="something"
//checking them
printenv ENV_VAR

//my scripts 
usr/local/bin

//a way to set up cron jobs
crontab -e 

//view a log file in real time
 tail -f /path/to/logfile

 //eviroment variables for specific user
 .bash_profile or .bashrc
 also .bashrc can be used kind of like an autoexec when you start a new terminal

 //mount local windows share
 sudo mount -t cifs -o user=toby,uid=gandalf,gid=devs //192.168.1.149/Shared /mnt/winShare

//ssh and google authenticator configs
sudo apt-get install libpam-google-authenticator
google-authenticator (set up auth key)
/etc/pam.d/sshd
auth required pam_google_authenticator.so (add at bottom)
/etc/ssh/sshd_config 
ChallengeResponseAuthentication yes (entry exist just change to yes)
sudo service ssh restart

//start a app on a remote desktop through ssh
DISPLAY=:0.0 [appToStart] &

//get server key fingerprint 
ssh-keygen -lf ssh_host_rsa_key.pub
//and if it doesn't display how you need it try this
awk '{print $2}' ssh_host_rsa_key.pub | base64 -d | sha256sum -b | awk '{print $1}' | xxd -r -p | base64

//run something on reboot for a user
//using crontab, can be used for forever script 
crontab -u user -e 
add this to the file:
@reboot /usr/local/bin/script

//change colors in console
vim ~/.bashrc
LS_COLORS=$LS_COLORS:'di=0;35:' ; export LS_COLORS

//....see size of current directory
du -sh 

..........mount a remote folder with sshfs...................
sudo sshfs -o allow_other,IdentityFile=[path_to_ssh_key] user@xxx.xxx.xxx.xxx:[path_to_remote_folder] [path_to_local_folder]


.......how to get the evn of a process....
ps -ef | grep [thing-you-want]
cd /proc/[process-id]
sudo cat eviron


......find process bound to port.....
lsof -i :port 

//.....vim......
//when you forget to sudo 
:w !sudo tee % 
//get to bottome of page
G$

//.....replace something across a repo or a dir in a repo
git grep -lz .js | xargs -0 sed -i '' -e 's/\.js/\.jsx/g'
//......replace extensions recursively in a dir
find . -name '*.js' -exec sh -c 'mv "$0" "${0%.js}.jsx"' {} \;

git grep -lz .jsxson | xargs -0 sed -i '' -e 's/\.jsxson/\.json/g'
find . -name '*.csm' -exec sh -c 'mv "$0" "${0%.csm}.css"' {} \;