Regular expressions (Bash)
To use regular expressions in Bash comparisons, use operator =~, like
if [[ "$switches" =~ [f] ]]; then echo "f - Create folder structure" mappenstructuur=true fi
I have the impression that regular expressions (regex) in Bash may not be the same as in MySQL, hence some more details in this article.
Match a substring
Probably the easiest case - No special characters or whatever needed:
i="blub"; [[ $i =~ blubber ]] && echo "i contains the substring 'blubber' " # False i="blub"; [[ $i =~ blub ]] && echo "i contains the substring 'blub' " # True
Match a single digit
[] denotes single character-comparison, meaning that the comparison is true as soon as the string contains one of the characters indicated within [].
[[ $i =~ [2] ]] && echo "i contains '2'" [[ $i =~ [12] ]] && echo "i contains '1' and/or '2'"
Match ranges of numbers or letters
i="blub"; [[ $i =~ [0-9] ]] && echo "i contains a number" # False i="blu1"; [[ $i =~ [0-9] ]] && echo "i contains a number" # True i="1111"; [[ $i =~ [0-9] ]] && echo "i contains a number" # True i="blub"; [[ $i =~ [A-Z] ]] && echo "i contains at least one uppercase letter" # False i="BLUB"; [[ $i =~ [A-Z] ]] && echo "i contains at least one uppercase letter" # True i="blub"; [[ $i =~ [a-z] ]] && echo "i contains at least one lowercase letter" # True i="blub"; [[ $i =~ [a-zA-Z] ]] && echo "i contains at least one letter" # True
Sequences
^: Beginning of the string$: End of the string
i="BLuB"; [[ $i =~ ^[A-Z]+$ ]] && echo "i contains only capital letters" # False i="BLUB"; [[ $i =~ ^[A-Z]+$ ]] && echo "i contains only capital letters" # True
Capture group
Really cool stuff: Substring extraction (Bash)