[ -f file.txt ] && echo "exists"

command1 && command2

command1 || command2

[ -d dirname ] && cd dirname

test -f file.txt && cat file.txt

for i in {1..10}; do echo $i; done

for file in *.txt; do echo $file; done

while [ $i -lt 10 ]; do echo $i; ((i++)); done

Практика: условия 1

Практика: циклы 1