Optional
Question mark in u? means u optional.
#!/bin/sh
: "Optional items
Question mark in colou?r means u optional
It is placed after the character that is optional
Grouping for optional, is one of the main uses of parantheses
"
A='color colour colur colou semicolon'
B='4 4th 4th?'
echo $A | grep 'colou?r' -o -E | tee result.txt
echo $B | grep '4(th)?' -o -E | tee result.txt -a
color
colour
4
4th
4th
Questions and answers
A regex containing optional metacharacter is always successful? [b,2]
- a) yes
- b) no
What is one of the main uses of parantheses? [b,2]
- a) grouping for negative
- b) grouping for optional
Which character is optional in colou?r
- a) u
- b) r
