shellFish
g++ shellFish.cpp -o shellFish && ./shellFish
echo $$
autocompetion using <tab> key.
echo HOST
root user (#) prompt,
normal user (%) prompt.
PS1="=>"
PS1=DEFAULT
cd ..
cd HOME
cd ~
alarm 4 you are late
cat a.txt | head -4 | tail -3 | sort
cat a.txt > op.txt
cat a.txt | head -4 | tail -3 | sort > op.txt
cat a.txt >> op.txt
./a.out < input
alias c = cat
### 1. alias: you should type like alias 'll = ls -la'(ignore the quotes, the space should be given as shown)
export a = string
export -p # print all
export -n keyname
### 2. export: type like 'export x = 3'(ignore the quotes, the space should be given as shown), export -p, export -n name
pwd
history
clear
open a.mp4
sleep 100 &
fg jobnumber
cat ok.txt | grep pattern
ls, echo, touch, mkdir, grep, pwd, cd, cat,
head, tail, chmod, exit, history, clear, cp