3: File and User Management

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This page is being built

https://raspberrytips.com/raspberry-pi-commands/#Raspbian_commands

File & Directory Commands

cat<file>: Displays content of a file (concatenate)
```
cat /home/pi/readme.txt
```

cd<path>: change directory (directs to specific directory in tree)

note, there must be a space after cd

cd /home/pi
cd   #by itself takes you home
cd ~  navigate to home directory
cd /  navigate to root directory
cd .. go up one level
cd - go back one level

chmod
- three things need to be set
  - who you are setting permissions to

u-owner of the file
g - the file group
o - everyone who is not owner
a- everyone

how you are setting the permissions

+ turns on a permission
- turns off a permission
= ignores current permissions and sets new ones

what you are setting them to

r read
w write
x execute
X special execute for folders

change permissions in a file

chmod 755 filename.txt  (gives all permissions)

cp<file or directory><destination>: Copies file or directory to new location, to include subfolders (all content) you need to add -r (recursive)

cp file.txt /home/pi/mydocuments
cp /home/pi/mydocuments/file.txt /home/pi/experiment_folder
cp -r /home/pi/mydocuments/ /home/pi/experiment_folder

cut cuts a portion of a file usning commas and delimeters.
- -d flag for delimiters

df -h

displays disk space and partitions

diff
find difference between two files

diff file1.txt file2.txt

find <file name>
program that allows you to find where particular types of data exists across directory structures.

find / -name passwd
find / -iname filename.ext  (not case sensitive)

Needs to be developed
grep <string><location>: (Global Regular Expression Print) Finds a string in a file or script
grep " " filename.txt

head <file>: Displays the head (beginning of a file)

head /home/experiments/lab1.txt
head -n20 /home/experiments/lab1.txt       (displays first 20 lines of lab1.txt

less

Allows scrolling with up/down arrows

less /home/experiments/lab1.txt

ls: list files and directories in the current folder (or a specific folder if specified)

ls
ls /home/pi
ls -1     (one, to make a single column)
ls -l      (long, to list info)
ls -l -a   (long and all, to include hidden files
ls ../   (reaches up one level)

mkdir <folder>: creates a new subfolder in the current folder, or the specified folder
```
mkdir <new folder name.>
mkdir /home/pi <new folder name
```

more<file>: Displays content of file, use enter or space to scroll through pages, q to quit. Often useful for monitoring logfiles
```
more /file_directory/filename.ext
more /var/log/slyslo
```

mv<source><destination>: moves a file or directory to a new location

mv /home/pi/work/myfile.txt / /hom/pi/experiments/
mv /home/pi/work/ /home/pi/experiments/

nano<file>: Linux text editor (CTRL+O, Enter of CRTL +X saves changes)
```
nano /home/pi/myscript.sh
```
ps aux

displays all running processes

ps -u pi

where pi is user name

pwd: Print current Working Directory (shows what directory you are in
```
pwd
```
reboot

sudo reboot

rm <file>: Deletes file, to delete a folder use -rf (recursive force)
```
rm myscipt.sh
rm -rf /home/pi/scripts
```
sed

can be used for find and replace with s flag

sed 's/bob/robert' filename.txt will replace bob with robert

shutdown

sudo shutdown -h now
sudo shutdown -h 12:05

sort

-k# flag sorts by column number

sort filename.txt

tail <file>: displays the end of a file (useful for seeing latest entries on logfiles)

tail /var/log/syslog
tail -n20 /var/log/syslog       (display twenty lines)
tail -f /var/sys/syslof            (displays new lines in real time)

tar

tar -c: store tar (compressed) files

tar -cvfz arcjove/tar/gz /home/pi/Documents/mydirectory
    -c creates archive
    -v verbose
    -f filename of archive to follow
    -z compress files with gzip

tar -x: extract files
```
tar -xvfz archive.tar.gz
```

tree: shows tree in directories
```
tree
```
uniq

filters out duplicate lines in a test file

wc: word count

wc -l line count

General Commands

clear : clears terminal screen
date : gives current date
history : Gives a history of commands the last time the pi was run
poweroff : Shuts the Pi down (Need to find keyboard shortcut)
echo

echo -n no new line

echo shows string/text that are used as arguments

>> appends to file

echo $! - gives the exit status of the last command

=0 means it ran fine
=1 means it hung up (terminated abruptly)

man

manual - gives options to a command, the following gives options for ls. Q gets you back to prompt

man ls

TOUCH
used to create any type of file with zero size

touch demo.txt

allows you to view a file. The following command allows you to see what your operating system is

cat does not support keyboard scrolling

 cat /etc/os-release

Network Commands

The Pi comes with two Network Interfaces, ethernet (eth0) and WiFi (wlan0)

Configuration

ipconfig: Diplays current IP donfiguation (ip a) is shortcut
```
ifconfig
ip a
```
netstat

shows every port that is open

ping<ip>: Sends ping package to another IP on network to see if host is up
```
ping 111.111.1.1
```

File Transfer-Remote Connection

wget<url> allows you to download a file from internet
```
wget https://URL
```
ssh<user>@<ip>: Protocol to allow you to remotely connect to computer over web.
```
ssh root@111.111.1.1
```

Package Management

apt-get install <package> installs a package
```
sudo apt-get install phpmyadmin
```
apt-get remove <package> removes previously installed package
apt-cache search <package name> searches for package name in package list (repository)
```
sudo apt-get search php
```
dpkg -l List installed packages on system. Can be used with grep to find specific package
dpkg -l
dpkg -l | grep myadmin

Raspbian Commands

raspi-config: allows you to manage configuation from terminal or ssh
```
sudo raspi-config
```
raspi-gpio: Allows you to control gpio ports
Need to develop
raspistill: takes an image with camera plugged to pi camera port
```
raspistill -o imag.jpg
```
raspivid: takes a video with camera, the time is in milliseconds
```
raspivid -o video.h264 -t 10000   
```
raspividyuv or raspiyuv: allows video stream
```
raspividyuv -o video.yuv
```

System Management

install

to install packages (need to fix)

sudo apt-get install vim  (to install the vim editor)

to remove a package

sudo apt-get remove vim  (to remove the vim editor)

dmesg

Shows all processes and error when system boots

htop: displays information on running processes (like top, but has more info)
```
htop
```

kill <pid>: kills a process by it's process ID (which you can get with the ps command)

kill 12345      (Kills process ID 12345, but does not step the script and goes onto the next command of the program)
kill 12345 -9  (Kills process 12345 and exits the program)

ps: displays running processes, to display everything
```
 ps aux
```
to display a specific user
```
ps -u pi
```
reboot : reboots the pi
```
sudo reboot
```
service <service name><action>: Allows you to start/stop services
service apache 2 start
service apache 2 stop
service apache2: (shows actions available for a service)
service apache 2
- update-rc.d<service><action>: On Debian, allows you to start/stop service on system boot
  sudo update-rc.d ssh enable
- update-rc.d -f ssh remove: Disables start of service (-f option "forces")
  sudo update-rc.d -f ssh remove

NOTE: These commands are only for services, to start other scripts/commands on boot you need to edit the local etc/rc/local file
sudo nano /etc/rc.local

shutdown -h now : shuts down (halts) the pi
```
sudo shutdown -h now
```
shutdown -h <time> : shuts the Pi at specific time
```
sudo shutdown -h 08:00
```
shutdown -r : shuts down and reboots the pi
sudo shutdown -r
top
- shows processes being run

vcgencmd measure_temp: Displays current CPU temperature
```
vcgencmd measure_temp
```

User Management

to add user

sudo adduser name-in-lower-case
sudo adduser bob

Figure $\PageIndex{1}$: Copy and Paste Caption here. (Copyright; author via source)

to change password

-note you will see no characters and it first asks for current password, and then for the new one twice

- if you have admin privledges you can

passwd
sudo passwd name (lets someone with sudo privledges make a password for someone else)
sudo passwd name -d  (deletes password)

System Updates

apt-get update: Use to synchronize your list of packages with the most, should be run before upgrading packages to ensure you have the most recent versions
```
sudo apt-get update
```
apt-get upgrade: Upgrades installed software packages
```
sudo apt-get upgrade
```
rpi-update: Updates everything (only use if you know what you are doing)

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