normoes

hidden files

create an archive using tar (including hidden files)

taken from Digitesters

Normally:

tar czf backup.tar.gz /backup/*

This way all files are tarred except the hidden files.

normoes

shifting bits

n << 1 == n * 2
n << 2 == n * 4
n << 3 == n * 8

n >> 1 == n / 2

normoes

binary math

source

2's complement

101 -> 010 + 1 = 011
11010 -> 00101 + 1 = 00110

binary subtraction

normoes

  $ namei -om ~/tmp/newnew/
  f: /home/user/tmp/newnew/
  drwxr-xr-x root   root   /
  drwxr-xr-x root   root   home
  drwxr-xr-x user user user
  drwxrwxr-x user user tmp
  drwxrwxr-x user user newnew

normoes

ssh-agent bash -c ' ssh-add ~/git_key/id_rsa; cd ~/some_git_repo; git pull'

normoes

docker cli

  -it

docker-compose

  stdin_open: true
  tty: true

normoes

    >>> import secrets
    >>> import string
    >>> print(''.join(secrets.choice(string.digits + string.ascii_letters + string.punctuation) for i in range(100)))

    *:}~{MH)D&e}SGYRcAO~Q}PFD@:bN$6\d2&A7VB.ge2<zGda5J#)(p>>_H5l*Z>Q9R+!lZ&yn-th2^0ZUf|tkQS8zQu&5+THw&}C

normoes

Like done in the official nginx docker image:

# forward request and error logs to docker log collector
RUN ln -sf /dev/stdout /var/log/nginx/access.log \
	&& ln -sf /dev/stderr /var/log/nginx/error.log

normoes

Run the container with:

--cap-add sys_admin --cap-add sys_ptrace 

Within the container:

apt-get strace

normoes

source

Redirect stdout to one file and stderr to another file:

command > out 2>error

Redirect stderr to stdout (&1), and then redirect stdout to a file:

command >out 2>&1