shell-commands.md

Notes about Shell Commands

In Linux or Unix, MacOS or WSL(Windows-Subsystem-for-Linux), terminal commands could be "fun" to use.

As an inexperienced developer, I would like to adapt more and panic less,

for example when login to a container console realizing I was trapped in Vim but only wish to edit a text file X(

I try to keep notes short and sweet.

(some usage might depend on OS)

Basics

Two files, concatenation with cat (and '>')

touch sample1
touch sample2
echo "123" > sample1
echo "abc" > sample2
cat sample1 sample2 > sample1_2
cat sample1_2 sample2 > sample1_2_2
cat sample1 sample2 sample1 > sample1_2_1

diff arg: -y compare side-by-side

diff sample1_2_1 sample2_2_1 -y

Print OS info

uname arg: a for all

man uname
uname -a

ps cmd list processes

arg: -A (capital)all users, -v verbose, -m sort by memory usage

ps -Avm

Parsing

grep

print matching lines with line number

cat sample1_2_1 | grep 5 -n

Novel

If I were an imaginary hacker and picky about not leaving trace...

appending a space to hide cmds outside history

history | tail
pwd 
history | tail

touch cmd changes modification time

ls -l
touch sample1_2_1
ls -l

shred cmd overwrites specified file(s) for harder discovery

arg: x for exactly same size

ls -l
shred sample1_2_2 -v -x
cat sample1_2_2

Vim

Navigation

Smart design of navigational control :P

(Use ESC to quit insert mode)

k:up, j:down, H:top, M:middle,

w:start-of-next-word, e:end-of-next-word, b:start-of-previous-word,

59gg:line-59,

fx:next-x, Fx:previous-x, ;:repeat-jump, ,:reverse-repeat-jump

General commands

:w write

:q quite

Collected articles

Medium: Simple commands like pro

Medium: Safer shell scripts