help/docs/help.md

# basic help

> *write in irc/matrix channel `#envs` or*<br />
> *contact [sudoers@envs.net](mailto:sudoers@envs.net) for any other help requests.*

## # show public ip
`curl ip.envs.net`

## # termbin - aliases
`echo 'alias tb="nc tb.envs.net 9999"' >> ~/.bash_aliases`

you can POST a text:<br />
&nbsp;&nbsp;`echo less typing now! | tb`

or Content of a file:<br />
&nbsp;&nbsp;`cat ~/some_file.txt | tb`<br />

## # the null pointer - aliases
add the following lines to you're aliases file `~/.bash_aliases`
```bash
0file() { curl -F"file=@$1" https://envs.sh ; }
0pb() { curl -F'file=@-;' https://envs.sh ; }
0url() { curl -F"url=$1" https://envs.sh ; }
0short() { curl -F"shorten=$1" https://envs.sh ; }
```
HTTP POST files here:<br />
&nbsp;&nbsp;`0file "yourfile.png"`

post your text directly:<br />
&nbsp;&nbsp;`echo "text here" | 0pb`

you can also POST remote URLs:<br />
&nbsp;&nbsp;`0url "https://example.com/image.jpg"`

or you can shorten URLs:<br />
&nbsp;&nbsp;`0short "https://example.com/some/long/url"`<br />
<br />
***if you want a nice wrapper, try [~tomasino's pb](https://git.envs.net/envs/pb)***

## # ssh
your ssh directory is: `~/.ssh/` this includes the following files.

- your ssh config file `~/.ssh/config` (more bellow)
- the `authorized_keys`-file is a list of public keys (one per line) that are allowed to log in to your user account.
- `id_ed25519` or `id_rsa` are each private keys, and `id_ed25519` or `id_rsa.pub` are the corresponding pubkey.

### ssh details and usage
ports 22, 80, 443, 2222 and 2223 are available for ssh.<br />
use ssh.envs.net to reach the secondary ip and use 80 and 443 for ssh.<br />
so, for example, you can do:<br />
&nbsp;&nbsp;`ssh user@envs.net`<br />
&nbsp;&nbsp;`ssh -p2223 user@envs.net`

or for the secondary ip:<br />
&nbsp;&nbsp;`ssh -p443 user@ssh.envs.net`<br />
<br />
***if you have a slightly shaky connection then you can also use `mosh`.***

### create a ssh-key
make sure you have a `~/.ssh directory`<br />
&nbsp;&nbsp;`mkdir -m 700 ~/.ssh`

create your key<br />
&nbsp;&nbsp;`ssh-keygen -t ed25519 -a 100`

your public and private key will be located at<br />
&nbsp;&nbsp;`cat ~/.ssh/id_ed25519.pub`

you can also use rsa:<br />
&nbsp;&nbsp;`ssh-keygen -t rsa -b 4096`<br />
&nbsp;&nbsp;`cat ~/.ssh/id_rsa.pub`

### ssh config
define ssh host aliase in `~/.ssh/config`
```bash
Host envs.net
  HostName envs.net
  Port 2223
  User user
  LocalForward localhost:6667 localhost:6667
```

now you can use a simple `ssh envs.net` to connect.<br />
there are tons of other options, including this `LocalForward` line to automatically set up the tunnel as show below.<br />
for more available options, see the man page: `man ssh_config`

### ssh tunnels
for example, you want to get into znc with your local client (weechat, etc),<br />
but your local network blocks znc ports. you can connect to envs.net, and use port forwarding to get on.

if you are connecting from a linux machine, you can do this:<br />
&nbsp;&nbsp;`ssh -L 6667:localhost:6667 envs.net`

after being logged in, open your local irc client, and use `127.0.0.1:6667`<br />
for your server setting. voila! you're now on envs.net znc server.<br />

what that ssh command did was open a local port tunnel (-L), using local port 6667 (6667:)<br />
pointed at localhost (from the remote's point of view), on remote port 6667 (default irc port).

putty has the same ability (for windows and mac users), under connection &gt; ssh &gt; tunnels.

you can do this for any arbitrary port.

### import &amp; authorize a public ssh-key
from URL (on remote machine)<br />
&nbsp;&nbsp;`echo $(curl -sL https://example.com/id_rsa.pub) | tee -a ~/.ssh/authorized_keys`

over ssh (on local machine)<br />
&nbsp;&nbsp;`ssh-copy-id -i ~/.ssh/id_rsa.pub -p2223 user@envs.net;`

### ssh remote execution
`ssh envs.net ping google.de`

or<br />
&nbsp;&nbsp;`ssh envs.net bash -c "'uname -a'"`

exec a local script<br />
&nbsp;&nbsp;`ssh envs.net 'bash -s' < local_script.sh`

## # scp usage
copy ssh pub key to remote:<br />
&nbsp;&nbsp;`scp -P 2223 ~/.ssh/authorized_keys user@envs.net:~/.ssh/authorized_keys`

copy website index.html from remote:<br />
&nbsp;&nbsp;`scp -P 2223 user@envs.net:~/public_www/index.html ~/public_www/`

## # rsync usage
sync website to remote:<br />
&nbsp;&nbsp;`rsync -avz -e "ssh -p 2223" ~/public_www user@envs.net:~`<br />
sync website from remote:<br />
&nbsp;&nbsp;`rsync -avz -e "ssh -p 2223" user@envs.net:~/public_www ~/`<br />

## # sftp usage
connect: `sftp -oPort=2223 user@envs.net`

### commands:
exit:	`exit`<br />
print help:	`help`

### transferring
files to remote:<br />
&nbsp;&nbsp;`put localfile remotefile`

dir to remote:<br />
&nbsp;&nbsp;`put -r localdir remotedir`

files from remote:<br />
&nbsp;&nbsp;`get remotefile localfile`

dir from remote:<br />
&nbsp;&nbsp;`get -r remotedir localdir`

### example:
add index.html to public_www Dir:<br />
&nbsp;&nbsp;`put public_www/index.html public_www`

add `~/.ssh/authorized_keys:`<br />
&nbsp;&nbsp;`put .ssh/authorized_keys .ssh/authorized_keys`

### single line usage (on local machine)
&nbsp;&nbsp;to remote:   `sftp -P 2223 user@envs.net:remotedir <<< $'put localfile_path'`<br />
&nbsp;&nbsp;from remote: `sftp -P 2223 user@envs.net:remotefile localfile`

## # your shell
avaliable shells: `ash`, `bash`, `csh`, `dash`, `elvish`, `fish`, `ksh`, `mksh`, `sash`, `sh`, `tcsh`, `xonsh`, `yash`, `zsh`<br />
*list all available shells: `more /etc/shells`*

to change your shell use: `chsh -s $(which <shell>)`<br />
or `chsh -s <path_to_shell>`

example: `chsh -s $(which bash)` or `chsh -s /bin/bash`

### default byobu-session
familiar with tmux, continue as normal, but with ctrl-a instead of ctrl-b<br>
if you don't want to this happen by default when you log in, run `byobu-disable`.<br>

`man byobu` for more info.

press shift-f1 for a full list of keybinds<br>
f2 creates a new tab<br>
f3 and f4 move you between tabs<br>
f6 disconnects and leaves everything running<br>
shift-f12 disable/enable byobu f-key bindings

## # timezone
The timezone by default on the server is UTC.

If you want to make it so that your shell prints out dates in localtime for you,<br />
run `tzselect` to find the correct timezone name that you’ll need to export as the TZ environment variable.

for example, if you’re in eastern time, add something like this<br />
`export TZ="America/Detroit"`<br />
to your .bashrc .

to get your timezone you can use `date`.

## # scheduled activity
the linux utilities `cron` and `at` are related commands. you might use crontab, for example, to perform a task each morning at 2 a.m., and use at to remind yourself of an appointment later in the day.

### cron/crontab
the cron utility allows you to schedule a repetitive task to take place at any regular interval desired.<br />
for more information see the manual pages of crontab(5) and cron(8)

display current crontabs:<br />
&nbsp;&nbsp;`crontab -l`

add/edit crontabs:<br />
&nbsp;&nbsp;`crontab -e`

example: - backup your mysql db once per day
```bash
..
# NOTE: * To disable email notifications use:
#         - for single cronjobs use after the cmd: >/dev/null 2>&1
#         - comment out to disable all email alerts in the crontab:
#MAILTO=""
# m h	dom	mon	dow	command
0 	0	*	*	*	/usr/local/bin/envs_mysql.sh backup
```

### at
the at command lets you specify a one-time action to take place at some desired time.<br />
for more information see the manual page of at.

examples:
```bash
# schedule task to execute just after 1 hour.
echo 'sh myscript.sh' | at now + 1 hour
# schedule task at 10:00 AM on coming sunday.
echo 'sh myscript.sh' | at 10:00 AM Sun
# schedule task to execute at midnight.
echo 'sh myscript.sh' | at midnight
```

view your at queue:<br />
&nbsp;&nbsp;`at -l` or `atq`<br />
`2       Sun Dec 29 14:03:00 2019 a creme`

delete at job id 2:<br />
&nbsp;&nbsp;`at -r 2` or `atrm 2`

## # daemonize processes
so you've got a process that you want to keep running. you might have it in a<br />
tmux or screen session. let's use systemd user units to manage it!

- ensure that your user unit loadpath is set up:<br />`mkdir -p ~/.config/systemd/user/`
- create a basic service. save something like this<br />in `~/.config/systemd/user/my-new-service.service` (adjusting where necessary)
```bash
[Unit]
Description=my script description
[Service]
ExecStart=/bin/bash -c "while true do; echo hi; done"
[Install]
WantedBy=default.target
```
- enable it:<br>`systemctl --user enable --now my-new-service.service`
- enable-linger for your user account:<br />`loginctl enable-linger`<br />this allows your user units to run even when you're not logged in.

done!<br />
you can now use `systemctl --user` to manage your daemonized process.