Merge branch 'dev' into vhs

2023-06-20 15:08:40 +02:00
parent fda9fcdec4 d10c6b2f9e
commit 4a9d2d61d2
105 changed files with 2494 additions and 3310 deletions
--- a/basics/at.md
+++ b/basics/at.md
@@ -4,29 +4,45 @@ tags: [ "Documentation", "Basics" ]
 ---
 Install with:

-> sudo apt install at
+```bash
+sudo apt install at
+```

 Enable the daemon service with:

-> sudo systemctl enable --now atd
+```bash
+sudo systemctl enable --now atd
+```

 Then jobs can be specified with absolute time, such as:

-> at 16:20
+```bash
+at 16:20
+```

-> at noon
+```bash
+at noon
+```

-> at midnight
+```bash
+at midnight
+```

-> at teatime
+```bash
+at teatime
+```

 Type in your command, e.g.:

-> touch /tmp/myFile.txt
+```bash
+touch /tmp/$FILE.txt
+```

 The jobs can also be specified relative to the current time:

-> at now +15 minutes
+```bash
+at now +15 minutes
+```

 Finally, accept the jobs with ^D.

@@ -34,15 +50,19 @@ Finally, accept the jobs with ^D.

 Display a list of commands to run with:

-> atq
+```bash
+atq
+```

-`2	Sat Oct 20 16:00:00 2018 a roach-1`
+> 2	Sat Oct 20 16:00:00 2018 a roach-1

 This will print all pending IDs.  Remove a job by the ID with:

-> atrm 2
+```bash
+atrm 2
+```

-Check /var/spool/atd/
+Check `/var/spool/atd/` to see the jobs.

 ![At it again](/tapes/at.gif)

@@ -50,10 +70,10 @@ Check /var/spool/atd/

 Automatically add a job for later, by setting the date, then using echo for the command.

-> t="$(date -d "2 minutes" +%R)"
-
-> echo "fortune > ~/file" | at "$t"
-
-> watch cat file
+```bash
+t="$(date -d "2 minutes" +%R)"
+echo "fortune > ~/$FILE" | at "$t"
+watch cat $FILE
+```

 The `$t` here outputs the day in minutes, but you could also do `t="$(date -d "2 days" +%m/%d/%Y)"`.
--- a/basics/basics.md
+++ b/basics/basics.md
@@ -9,91 +9,136 @@ Don't worry about understanding any of it, just type it in and the habit forms p

 You start in a dark room. You want to know where you are by **p**rinting out your **w**orking '**d**irectory' (i.e. 'location'):

-> pwd
+```bash
+pwd
+```

 Have a look at what is here:

-> ls
+```bash
+ls
+```

 If you get no response, the list of items is "", meaning "nothing here".

 Have a look at **a**ll the files:

-> ls -a
+```bash
+ls -a
+```

-`. ..`
+```bash
+. ..
+```

 So `.` means 'here' and `..` means 'you see stairs leading downwards' (e.g. 'the directory behind you').

 Change directory (`cd`) down one level:

-> cd ..
+```bash
+cd ..
+```

 Look where you are again with `pwd`, then go back up.  Use `ls`, and if you see `bob`, then:

-> cd bob
+```bash
+cd bob
+```

 Move around the directories.  The place at the bottom is the 'root', and is known as `/`.  Go to the root:

-> cd /
+```bash
+cd /
+```

-Do `ls` again and change into `etc`.  Look at how much space those folders are taking up:
+Do `ls` again and `cd` into `etc`.  Look at how much space those folders are taking up:

-> du iptables
+```bash
+du iptables
+```
+That's the number of kilobytes the file is taking up.
+Do the same again, but in a human-readable format:

-That's the number of kilobytes the file is taking up.  Do the same again, but in a human-readable format:
+```bash
+du -h iptables
+```

-> du -h iptables
+The `du` program has `-h` for 'human', '-s' for 'short', and a bunch of other commands.
+Have a look at the manual and try another command:

-The `du` program has `-h` for 'human', '-s' for 'short', and a bunch of other commands.  Have a look at the manual and try another command:
-
-> man du
+```bash
+man du
+```

 Once you're done, press 'q' to quit the manual page and try the extra `du` flag you've found.

 Now you can try to gain super-powers and take over the system:

-> sudo -i
+```bash
+sudo -i
+```

-At this point, you are 'root'. All your commands will be executed, even if they're unsafe, or even if you ask to delete the entire machine.  Best to exit out of the root account:
+At this point, you are 'root'.
+All your commands will be executed, even if they're unsafe, or even if you ask to delete the entire machine.
+Best to exit out of the root account:

-> exit
+```bash
+exit
+```

 Go find a file that isn't a directory.  You can tell which is which with:

-> ls -l
+```bash
+ls -l
+```

 A directory starts with a 'd', like this:

-`drwxr-xr-x 79 root root 4096 Jan  3 05:15 /etc/`
+```bash
+drwxr-xr-x 79 root root 4096 Jan  3 05:15 /etc/
+```

 A standard file starts with '-', like this:

+```bash
 `-rw-r--r-- 1 root root 8 Dec 11 17:26 hostname`
+```

 Look inside the file /etc/hostname to find out your computer's name:

-> cat /etc/hostname
+```bash
+cat /etc/hostname
+```

 Print out the words "hello world":

-> echo "hello world"
+```bash
+echo "hello world"
+```

 Move back to your home directory:

-> cd
+```bash
+cd
+```

 Take the words 'hello world', and put them in 'my_file':

-> echo 'hello world' > my_file
+```bash
+echo 'hello world' > my_file
+```

 Measure the disk usage of that file, then put the results at the bottom of the file:

-> du my_file >> my_file
+```bash
+du $FILE >> $FILE
+```

 And check the results:

-> cat my_file
+```bash
+cat $FILE
+```

 # Autocompletion

@@ -103,50 +148,70 @@ Press tab after typing a few keys and bash will guess what you're trying to  typ

 Look at your file's owner:

-> ls -l my_file
+```bash
+ls -l $FILE
+```

 If it says `-rw-r--r-- 1 root root 8 Dec 11 17:26 hostname` then the file is owned by 'root'.

 Take your file and change the owner to root:

-> sudo chown root my_file
+```bash
+sudo chown root $FILE
+```

 Change the same file so it's owned by the group 'audio':

-> sudo chown :audio my_file
+```bash
+sudo chown :audio $FILE
+```

 Check you did that correctly:

-> ls -l my_file
+```bash
+ls -l my_file
+```

-`-rw-r--r-- 1 root audio 0 Jan  3 19:20 my_file`
+> -rw-r--r-- 1 root audio 0 Jan  3 19:20 my_file

 Read the start of that line.  Root can 'read' and 'write' to or delete the file.  Try to remove (delete) it:

-> rm my_file
+```bash
+rm $FILE
+```

 You'll see you're not allowed, because you don't own it.

 Look at which groups you're in:

-> groups
+```bash
+groups
+```

 Change the file so that members of the audio group can write to the file:

-> sudo chmod g+w my_file
+```bash
+sudo chmod g+w $FILE
+```

 Check you got it right with `ls -l`:

-> -rw-rw-r-- 1 root audio 0 Jan  3 19:20 my_file
+```bash
+-rw-rw-r-- 1 root audio 0 Jan  3 19:20 my_file
+```

 Try to delete the file again:

-> rm my_file
+```bash
+rm my_file
+```

 If you can't, you're not in the audio group.  Add yourself.  You'll need to *modify* your *user account*, by **a**ppending 'audio' to your list of groups.
 Use `-a` to **a**ppend, and `-G`, to say you're modifying groups:

-> sudo usermod -a -G audio [ your username here ]
+```bash
+sudo usermod -a -G audio [ your username here ]
+```

 Now you should be able to remove (delete) the file.  Remember, that using 'rm file' will not send it to a recycling bin. The file is gone.

@@ -154,59 +219,83 @@ Now you should be able to remove (delete) the file.  Remember, that using 'rm fi

 Make a directory called 'new test':

-> mkdir 'new test'
+```bash
+mkdir 'new test'
+```

 Make two directories, called 'A', and 'Z':

-> mkdir A Z
+```bash
+mkdir A Z
+```

 Make a single directory called 'A Z'

-> mkdir 'A Z'
+```bash
+mkdir 'A Z'
+```

 # Text Searches

 Measure the disk usage of everything ('\*' means 'everything'), and put it in a file called 'disk usage.txt':

-> du -sch * > A/'disk usage'.txt
+```bash
+du -sch * > A/'disk usage'.txt
+```

 Look at your file:

-> cat A/'disk usage.txt'
+```bash
+cat A/'disk usage.txt'
+```

 If you think you have too much information, use `grep` to just get the one line of text you want:

-> grep total A/disk\ usage.txt
+```bash
+grep total A/disk\ usage.txt
+```

 The `grep` program also has a manual ('man page').  You should find out what that `-c` flag does, but the manual is too long to read.

 Start the manual:

-> man du
+```bash
+man du
+```

 Then search for `-c` by pressing `/`.  Your final keys should be `man du`, then `/-c`

 Find out if the `ls` program also has a 'human readable' format by using `grep` to search for the word 'human':

-> man ls | grep human
+```bash
+man ls | grep human
+```

 Now use that flag that you've found in combinatin with the `-l` flag to look at a file.

 Remove the directory 'Z':

-> rmdir Z
+```bash
+rmdir Z
+```

 Remove the directory 'Z':

-> rmdir Z
+```bash
+rmdir Z
+```

 And then remove all the rest:

-> rmdir *
+```bash
+rmdir *
+```

 The 'A' directory will not budge because it's not empty.  Remove it recursively, so the computer will remove the things inside the directory as well as the directory itself:

-> rm -r A
+```bash
+rm -r A
+```

 # Installation

@@ -214,34 +303,48 @@ You get a package manager which installs programs, fonts, et c.
 If you're on something like Debian, you'll have `apt`, or if you're on something like Red Hat, you'll have `yum`.
 If unsure, ask where a program is:

-> whereis yum
+```bash
+whereis yum
+```

-> whereis apt
+```bash
+whereis apt
+```

 If you get a hit, you can use whatever program that is to install things.

 Set a reminder of your package manager:

-> echo my package manager is yum | lolcat
+```bash
+echo my package manager is yum | lolcat
+```

 If that failed it's because you don't have `lolcat` installed.
 Install lolcat:

-> sudo apt install lolcat
+```bash
+sudo apt install lolcat
+```

 Try the same command again.

 Search for things you want, like `libreoffice`, or `gimp`:

-> apt search libreoffice
+```bash
+apt search libreoffice
+```

 ... then install one of them with:

-> apt install [ thing ]
+```bash
+apt install $PROGRAM
+```

 Remove `lolcat`, because it's useless:

-> sudo apt remove lolcat
+```bash
+sudo apt remove lolcat
+```

 ... and that's pretty much it.  You can move, create, destroy, install things, and look things up.

--- a/basics/clock.md
+++ b/basics/clock.md
@@ -5,27 +5,39 @@ tags: [ "Documentation", "Basics" ]

 Show system time:

-> date
+```bash
+date
+```

 Show hardware time:

-> sudo hwclock -r
+```bash
+sudo hwclock -r
+```

 Change system time to match hardware time:

-> sudo hwclock --hctosys
+```bash
+sudo hwclock --hctosys
+```

 Change hardware time to match system time:

-> sudo hwclock --systohc
+```bash
+sudo hwclock --systohc
+```

 Manually set the hardware time to a specified date:

-> sudo hwclock --set --date="8/25/19 13:30:00"
+```bash
+sudo hwclock --set --date="8/25/19 13:30:00"
+```

 ## Normal Date

-> date +%d/%m/%y
+```bash
+date +%d/%m/%y
+```

 # Unix Time

@@ -33,7 +45,9 @@ Computers started counting time on January 1st, 1970, and added one second-per-s

 Track the time in Unix-time:

-> date +%s
+```bash
+date +%s
+```

 # Network Time Providers

@@ -41,9 +55,13 @@ Servers which take their time from an observatory we call Stratum 1 servers.  Se

 Install ntp with:

-> sudo apt-get install -y ntp
+```bash
+sudo apt-get install -y ntp
+```

 The shell command for this is `ntpq`.  Monitor the service providers using:

-> ntpq -p
+```bash
+ntpq -p
+```

--- a/basics/conditionals.md
+++ b/basics/conditionals.md
@@ -41,29 +41,28 @@ case $CRE in
        owlbears | monsters ) echo "Really you're a wizard fan"
 ;;
 esac
+```

 # While and Until
 This prints from 1 until 9.

-> COUNTER=1
-
-> while [ $COUNTER -lt 2 ]; do
-
+```bash
+COUNTER=1
+while [ $COUNTER -lt 2 ]; do
        > ((COUNTER++))
-
        > echo $COUNTER
-
 > done
-
 ```

 There's also 'until', which stops when something is true, rather than keeping going when something is true.

 # For

-> for i in $( ls ); do
+```bash
+for i in $( ls ); do
 > 	du -sh $i
 > done
+```

 # Sequences

@@ -71,13 +70,19 @@ The sequences tool counts up from X in jumps of Y to number Z.

 Count from 1 to 10.

-> seq 10
+```bash
+seq 10
+```

 Count from 4 to 11.

-> seq 4 11
+```bash
+seq 4 11
+```

 Count from 1 to 100 in steps of 5.

-> seq 1 5 100
+```bash
+seq 1 5 100
+```

--- a/basics/cron.md
+++ b/basics/cron.md
@@ -6,24 +6,29 @@ tags: [ "Documentation", "Basics" ]

 The crontab program might have various names, like `cronie` or `crond`.

-> sudo apt search -n ^cron
+```bash
+sudo apt search -n ^cron
+```

 Once installed, search for the service name, and start it.

-> sudo systemctl list-unit-files | grep cron
+```bash
+sudo systemctl list-unit-files | grep cron
+```

-> sudo systemctl enable --now cron
+```bash
+sudo systemctl enable --now cron
+```

 You can *e*dit your crontab with:

-> crontab -e
-
-
+```bash
+crontab -e
 ```

-39 */3 * * * /usr/bin/updatedb

-```
+> 39 */3 * * * /usr/bin/updatedb
+
 ## Syntax

 `* * * * *`
@@ -34,29 +39,33 @@ These five points refer to:

 So '3pm every Sunday' would be:

-`0 15 * * 7`
+> 0 15 * * 7

 Here 'Sunday' is indicated by "7", and '3pm' is 'the 15th hour'.
 The minute is '0' (i.e. '0 minutes past three pm').

 Doing the same thing, but only in February, would be:

-`0 15 * 2 7`
+> 0 15 * 2 7

 ### Full Paths

 Executing something requires the full path to where it is, so you cannot simply use `apt update -y`, because cron does not know where `apt` is.
 Instead, find out where it is:

-> type -P apt
+```bash
+type -P apt
+```

 `/usr/bin/apt`

 Then put that into the crontab:

-> sudo crontab -e
+```bash
+sudo crontab -e
+```

-`40 */3 * * * /usr/bin/apt update -y`
+> 40 */3 * * * /usr/bin/apt update -y

 This will run `apt update -y` as root every 3 hours, at 40 minutes past the hour, e.g. 00:40, 03:40, 06:40.

@@ -65,13 +74,17 @@ This will run `apt update -y` as root every 3 hours, at 40 minutes past the hour
 You can execute a script as root by putting it into a directory, instead of in the tab.
 Look at the available cron directories:

-> ls /etc/cron.\*
+```bash
+ls /etc/cron.\*
+```

 ### Testing with runparts

 Run-parts runs all executable scripts in a directory.

-> run-parts /etc/cron.hourly
+```bash
+run-parts /etc/cron.hourly
+```

 ## Tips

@@ -84,12 +97,16 @@ First add `HOME=/home/user`, then you can use syntax like this:

 *Remember to test the script by executing that line first*:

-> $HOME/.scripts/myScript.sh
+```bash
+$HOME/.scripts/myScript.sh
+```

 You can also add your regular path to your crontab as a variable (see example below).
 If you're using vim as the editor, just run this at the top of your crontab:

-> :r!echo PATH=$PATH
+```bash
+:r!echo PATH=$PATH
+```

 ### `date` Commands

--- a/basics/kernel.md
+++ b/basics/kernel.md
@@ -10,17 +10,25 @@ Kernel modules live in lib/modules/$(uname -r)

 Load them with

-> sudo modprobe ath9k
+```bash
+sudo modprobe ath9k
+```

 Or remove one with

-> sudo modprove uvcvideo
+```bash
+sudo modprove uvcvideo
+```

 The PC's irritating speaker beep can be really annoying. Disable it with:

-> sudo modprobe -r pcspeaker
+```bash
+sudo modprobe -r pcspeaker
+```

 Permanently disable a module by blacklisting it in `/etc/modprobe.d`:

-> echo 'blacklist pcspkr' > /etc/modprobe.d/*nobeep*.conf
+```bash
+echo 'blacklist pcspkr' > /etc/modprobe.d/*nobeep*.conf
+```

--- a/basics/kill.md
+++ b/basics/kill.md
@@ -7,7 +7,9 @@ If you want to kill a program in a graphical environment, open a terminal and ty

 # Graphical Programs

-> xkill
+```bash
+xkill
+```

 Then click on the application which you want to kill.

@@ -15,23 +17,31 @@ Then click on the application which you want to kill.

 To kill a program, find it with:

-> pgrep discord
+```bash
+pgrep discord
+```

 This will give you the UUID, e.g. `19643`.

 Kill the program with:

-> kill 19643
+```bash
+kill 19643
+```

 # Types of Kill

 To see an ordered list of termination signals:

-> kill -l
+```bash
+kill -l
+```

- 1) SIGHUP   2) SIGINT   3) SIGQUIT  4) SIGILL   5) SIGTRAP
- 6) SIGABRT  7) SIGBUS   8) SIGFPE   9) SIGKILL 10) SIGUSR1
-11) SIGSEGV 12) SIGUSR2 13) SIGPIPE 14) SIGALRM 15) SIGTERM
+> 1) SIGHUP   2) SIGINT   3) SIGQUIT  4) SIGILL   5) SIGTRAP
+
+> 6) SIGABRT  7) SIGBUS   8) SIGFPE   9) SIGKILL 10) SIGUSR1
+
+> 11) SIGSEGV 12) SIGUSR2 13) SIGPIPE 14) SIGALRM 15) SIGTERM


 You can select these levels with a '- number'.
@@ -39,18 +49,24 @@ Higher numbers are roughly equivalent to insistence.

 For example:

-> kill -1 3498
+```bash
+kill -1 3498
+```

 This roughly means 'maybe stop the program, if you can, maybe reload'.

 Or the famous:

-> kill -9 3298
+```bash
+kill -9 3298
+```

 This means 'kill the program dead, now, no questions, dead'.

 **Beware** - if Firefox starts another program to connect to the internet, and you `kill -9 firefox`, this will leave all of Firefox's internet connection programs ("children") still there, but dead and useless.

+# Sobriquets
+
 - A dead program which sits there doing nothing is known as a 'zombie'.
 - A program which is run by another program is called a 'child program'.
 - A child whose parent program is dead is called an 'orphan'.
--- a/basics/links.md
+++ b/basics/links.md
@@ -4,12 +4,16 @@ tags: [ "Documentation", "Basics" ]
 ---
 Link from X to Y.

-> ln -s X ../otherdir/Y
+```bash
+ln -s X ../otherdir/Y
+```

 If you want a hard link, this will make a single file exist in two locations.
 If it is deleted in one location, it continues to exist in the other.

-> ln *X* *Y*
+```bash
+ln *X* *Y*
+```

 Both files must be on the same hard drive, as they have the same inode (check this with `ls -i file`).

--- a/basics/locale.md
+++ b/basics/locale.md
@@ -3,29 +3,40 @@ title: "locale"
 tags: [ "Documentation", "Basics" ]
 ---

+Your locale tells the computer your location, preferred time-and-date format, standard language, papersize, et c.
 A list of supported locales is available at /usr/share/i18n/SUPPORTED

 See a full list with:

-> cat /usr/share/i18n/SUPPORTED
+```bash
+cat /usr/share/i18n/SUPPORTED
+```

 Take the first portion to generate full locale information for a region:

-> locale-gen ru_RU.UTF-8
+```bash
+locale-gen ru_RU.UTF-8
+```

 Then use this for the current shell session with

-> LANG=ru_RU.utf8
+```bash
+LANG=ru_RU.utf8
+```

 Expand this to the entire system with: 

-> export LANG=ru_RU.utf8
+```bash
+export LANG=ru_RU.utf8
+```

 You can make this permanent for one user by adding this line to the ~/.profile or ~/.bashrc.

 Make it permanent for the entire system by editing:

-> sudo vim /etc/defaults/locale
+```bash
+sudo vim /etc/defaults/locale
+```

 # Variables

--- a/basics/locating.md
+++ b/basics/locating.md
@@ -6,7 +6,9 @@ tags: [ "Documentation", "Basics" ]

 `type` shows what kind of thing you're running, be it an alias, function, or binary program.

-> type cmus
+```bash
+type cmus
+```

 ![where is cmus?](/tapes/which.gif)

@@ -18,18 +20,24 @@ Ask where the `angband` program is, along with all its configuration files:

 Also `which` shows where a binary file (the program) is, 

-> which cmus
+```bash
+which cmus
+```

 # Quick Search for Files

 You'll need to set up `locate` for this by installing `mlocate`.
 `mlocate` needs a list of all files on the machine, so run:

-> sudo updatedb
+```bash
+sudo updatedb
+```

 Then to find a file called 'my-cats.jpg', run:

-> locate cats
+```bash
+locate cats
+```

 For best results, run `updatedb` regularly, perhaps in crontab.

--- a/basics/processes.md
+++ b/basics/processes.md
@@ -6,23 +6,33 @@ tags: [ "Documentation", "Basics" ]

 See running items in current terminal with 

-> ps
+```bash
+ps
+```

 or more with 

-> ps -a
+```bash
+ps -a
+```

 Or the entire system with

-> ps -e
+```bash
+ps -e
+```

 Or the entire system with more information, BSD style, with:

-> ps aux
+```bash
+ps aux
+```

 And then search for a particular program with 

-> ps aux | grep cmus
+```bash
+ps aux | grep cmus
+```

 # Jobs

@@ -30,15 +40,21 @@ Pause a job with ^z.  Put it in the background with the '&' suffix.

 List jobs in the current shell with

-> jobs
+```bash
+jobs
+```

 And then you can pull number 1 up again with 

-> fg 1
+```bash
+fg 1
+```

 Or continue running a stopped job with:

-> bg 1
+```bash
+bg 1
+```

 # Nice

@@ -46,21 +62,31 @@ This changes how nice a program is, from -20 to 19.

 Install a program, but nicely, at nice value '10':

-> nice -10 sudo apt -y install libreoffice
+```bash
+nice -10 sudo apt -y install libreoffice
+```

 Aggressively use Steam, with a nice value of '-13'.

-> nice --13 steam&
+```bash
+nice --13 steam&
+```

 Find out that Steam's fucking everything up, so you change its nice value with 'renice':

-> renice --5 -p 3781
+```bash
+renice --5 -p 3781
+```

 Nerf all of roach-1's processes:

-> renice 10 -u roach-1
+```bash
+renice 10 -u roach-1
+```

 ... or the entire group

-> renice -14 -g hackers
+```bash
+renice -14 -g hackers
+```

--- a/basics/time.md
+++ b/basics/time.md
@@ -6,7 +6,9 @@ tags: [ "Documentation", "Basics" ]

 Set time to synchronize with an ntp server:

-> timedatectl set-ntp true
+```bash
+timedatectl set-ntp true
+```

 This info stays in `/usr/share/zoneinfo`.

@@ -16,7 +18,9 @@ Local time is kept in /etc/localtime.

 According to Dave's LPIC guide, you can set the local time by making asymboling link from your timezone to /etc/localtime, as so:

-> sudo ln -sf /usr/share/zoneinfo/Europe/Belgrade /etc/localtime
+```bash
+sudo ln -sf /usr/share/zoneinfo/Europe/Belgrade /etc/localtime
+```

 ...however this produced the wrong time for me.  Further, /etc/localtime produces an output with cat, while the zoneinfo files do not.

@@ -24,23 +28,33 @@ According to Dave's LPIC guide, you can set the local time by making asymboling

 See local time, language and character settings with:

-> locale
+```bash
+locale
+```

 List available locales with:

-> locale -a
+```bash
+locale -a
+```

 To see additional locales which are available (but not necessarily installed):

-> cat /usr/share/i18n/SUPPORTED
+```bash
+cat /usr/share/i18n/SUPPORTED
+```

 Set a supported locale with:

-> locale-gen pl_PL.UTF-8
+```bash
+locale-gen pl_PL.UTF-8
+```

 Then set that language, with:

-> LANG=pl_PL.UTF-8
+```bash
+LANG=pl_PL.UTF-8
+```

 ... then reboot.

@@ -48,7 +62,9 @@ Then set that language, with:

 Glimpse an overview with:

-> ntpq -p
+```bash
+ntpq -p
+```

 Usually this is run as a service, so just start that service.

--- a/basics/users.md
+++ b/basics/users.md
@@ -6,91 +6,133 @@ tags: [ "Documentation", "Basics" ]

 Let's get some entries with 'getent', e.g. passwd or group.

-> getent passwd
+```bash
+getent passwd
+```

-> getent group
+```bash
+getent group
+```

 Obviously:

-> getent shadow
+```bash
+getent shadow
+```

 ## Examples

-> sudo adduser maestro 
+```bash
+sudo adduser maestro 
+```

 add user 'maestro'

 This depends upon the settings in the /etc/default/useradd file and /etc/login.defs

-> sudo useradd -m pinkie 
+```bash
+sudo useradd -m pinkie 
+```

 add user 'pinkie' with a home directory

-> sudo adduser -m -e 2017-04-25 temp 
+```bash
+sudo adduser -m -e 2017-04-25 temp 
+```

 add expiry date to user

-> userdel maestro 
+```bash
+userdel maestro 
+```

 delete maestro

-> userdel -r maestro 
+```bash
+userdel -r maestro 
+```

 delete maestro and hir homefolder

-> groups 
+```bash
+groups 
+```

 find which group you are in


-> id 
+```bash
+id 
+```

 same

-> id -Gn maestro 
+```bash
+id -Gn maestro 
+```

 Find which groups maestro is in


-> deluser --remove-home maestro 
+```bash
+deluser --remove-home maestro 
+```

 delete user maestro


-> usermod -aG sudo maestro 
+```bash
+usermod -aG sudo maestro 
+```

-add user maestro to group sudo
+Add user maestro to group sudo:


-> cat /etc/passwd 
+```bash
+cat /etc/passwd 
+```

 list users' passwords (and therefore users)

-> groupadd awesome 
+```bash
+groupadd awesome 
+```

 create the group 'awesome'

- passwords are stored in /etc/shadow.
+Passwords are stored in /etc/shadow.

- there are user accounts for processes such as 'bin' and 'nobody' which are locked, so they're unusable.
+There are user accounts for processes such as 'bin' and 'nobody' which are locked, so they're unusable.

-> passwd -l bin 
+```bash
+passwd -l bin 
+```

-lock the user 'bin'
+Lock the user 'bin'.

-> more /etc/passwd | grep games 
+```bash
+more /etc/passwd | grep games 
+```

 we find the name, password and user id of the user 'games'. I.e. the password is 'x', and the user id is '5'.  The password is an impossible hash, so no input password could match.

-> groupdel learners | delete the group 'learners'
+```bash
+groupdel learners | delete the group 'learners'
+```

-> gpasswd -d pi games | remove user 'pi' from the group 'games'
+```bash
+gpasswd -d pi games | remove user 'pi' from the group 'games'
+```

-> id games 
+```bash
+id games 
+```

 find the id number of group 'games' (60)

-> usermod -aG sudo maestro 
+```bash
+usermod -aG sudo maestro 
+```

 add user to group 'maestro'

@@ -114,7 +156,9 @@ Alternatively, change the shell in /etc/passwd.

 Usermod also lets you change a user's username:

-> usermod -l henry mark
+```bash
+usermod -l henry mark
+```

 However, this will not change the home directory.

@@ -126,7 +170,9 @@ usermod -L henry

 -G or -groups adds the user to other groups:

-> usermod -G sudo henry
+```bash
+usermod -G sudo henry
+```

 -s adds the user to a shell.

@@ -140,45 +186,53 @@ In /etc/group, a group file may look like this:

 We can use groupmod, like like usermod, e.g. to change a name:

-> groupmod -n frontoffice backoffice
+```bash
+groupmod -n frontoffice backoffice
+```

 Delte a group:

-> groupdel frontoffice
+```bash
+groupdel frontoffice
+```

 # Logins

 See list of logged on users.

-> w
+```bash
+w
+```

 See last logons:

-> last
+```bash
+last
+```

 or all logon attempts, including bad attempts:

-> lastb
+```bash
+lastb
+```

 List recently accessed files:

-> last -d
+```bash
+last -d
+```

 See files opened by steve

-> lsof -t -u steve
+```bash
+lsof -t -u steve
+```

 See files opened by anyone but steve

-> lsof -u ^steve
-
-Fuser can also track people loggingin:
-
-> fuser /var/log/syslog
-
-... and fuser can kill everything accessing the home directory:
-
-> fuser -km /home
+```bash
+lsof -u ^steve
+```

 # Looking for Dodgy Files

@@ -186,21 +240,29 @@ Some files can be executed by people as if they had super user permissions, and

 Let's start with files executable by user:

-> sudo find / -type f -perm -g=s -ls
+```bash
+sudo find / -type f -perm -g=s -ls
+```

 And then those executable by the group:

-> find / -type f -perm -g=s -ls
+```bash
+find / -type f -perm -g=s -ls
+```

 And finally, worrying files, executable by anyone as if sie were the owner:

-> find / -xdev \( -o -nogroup \) -print
+```bash
+find / -xdev \( -o -nogroup \) -print
+```

 Then have a look at resource usage per user.

-#SGID
+# SGID

-> sudo chmod u+s process.sh
+```bash
+sudo chmod u+s process.sh
+```

 This will modify process.sh to that instead of being simply executable, anyone executing it will have the permissions as if owner while executing it.