Given a text file file.txt that contains list of phone numbers (one per line), write a one liner bash script to print all valid phone numbers.
You may assume that a valid phone number must appear in one of the following two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)
You may also assume each line in the text file must not contain leading or trailing white spaces.
For example, assume that file.txt has the following content:
987-123-4567 123 456 7890 (123) 456-7890
Your script should output the following valid phone numbers:
987-123-4567 (123) 456-7890
考察Linux查找文本的操作，主要是命令与正则表达式
# Read from the file file.txt and output all valid phone numbers to stdout. # No.1 grep -e "^[0-9]\{3\}-[0-9]\{3\}-[0-9]\{4\}$" -e "^([0-9]\{3\}) [0-9]\{3\}-[0-9]\{4\}$" file.txt # No.2 grep -e "^\([0-9]\{3\}-\|([0-9]\{3\}) \)[0-9]\{3\}-[0-9]\{4\}$" file.txt