ipan

Example config for mac only

Host bastion
  Hostname ssh-bastion.example.com
  IdentityFile ~/.ssh/bastion_ssh.key
  User bastion-user

# internal server on private network
Host 172.18.* 192.168.*

ProxyJump bastion

ipan

"""
For Python ≥ 3.2, os.makedirs has an optional third argument exist_ok that, when true, enables the mkdir -p functionality -- unless mode is provided and the existing directory has different permissions than the intended ones; in that case, OSError is raised as previously.
"""

import errno
import os

def mkdir_p(path):
    try:
        os.makedirs(path)

ipan

Using sed to append something after search pattern.

sed -i '/PATTERN/a\APPENDED' <file>

For example, this will add "sample": "sample x", after "flows": .*, to test_inactive.json

sed -i '/"flows": .*,/a\ "sample": "sample x",' test.json

ipan

# only add when the json file does not have new line
git ls-files | grep json | while read f; do tail -n1 $f | read -r _ || echo >> $f; done

# https://unix.stackexchange.com/questions/31947/how-to-add-a-newline-to-the-end-of-a-file
# https://unix.stackexchange.com/questions/192786/what-is-the-meaning-of-read-r

ipan

# jq can not write back to the same file
for i in `find . -name '*.json'`
do
    jq '.' $i > $i.tmp
    mv $i.tmp $i
done

# oneliner version
# for i in `find . -name '*.json'`; do jq '.' $i > $i.tmp && mv $i.tmp $i; done

ipan

do not check host key

ssh -o StrictHostKeyChecking=no user@ssh-server

.ssh/config settings for all hosts with DSA

PubkeyAcceptedKeyTypes=+ssh-dss
KexAlgorithms +diffie-hellman-group1-sha1

https://www.mostlynetworks.com/2016/10/fixing-macos-sierraopenssh-7-x-compatibility/

ipan

find out what process is binding the port 4000 with lsof

lsof -i tcp:4000

and use netstat

netstat -lnt -p tcp

ipan

$ nproc
32


$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                32
On-line CPU(s) list:   0-31

ipan

creating swap

This is how to format swap partition

mkswap /dev/data/swap

shell output:

mkswap: /dev/data/swap: warning: don't erase bootbits sectors

on whole disk. Use -f to force.

ipan

scroll up and down

Ctrl-A [

This will activate copy mode in GNU/screen. Now, you can scroll up/down and look at your data. Use the following keys:

1. Ctrl-u and Ctrl-d scroll the display up/down by the specified amount of lines while preserving the cursor position. (Default: half screen-full).
2. Ctrl-b and Ctrl-f scroll the display up/down a full screen.