How can I find a digit after string with pattern?

Question

I'm trying to get the last return code from an SSH shell in linux. I'm using the command:echo &? to get it. I've written following code but it's not working:

int last_len = 0;
Pattern p = Pattern.compile("echo $?\r\n[0-9]");
while(in.available() > 0 ) {
    last_len = in.read(buffer);
    String str = new String(buffer, 0, last_len);
    Matcher m = p.matcher(str);
    if(m.find()) {
        return Integer.parseInt(m.group().substring(9));
    }
}

What am I doing wrong?

Avinash Raj · Accepted Answer · 2015-07-23 07:36:28Z

1

You need to escape $, ? in the regex inorder to match the literal form of those characters since ?, $ are considered as special chars in regex.

Pattern p = Pattern.compile("echo \\$\\?\\r?\\n([0-9])");
Matcher m = p.matcher(str);
if(m.find()) {
System.out.println(m.group(1));
}

or

Pattern p = Pattern.compile("echo\\s+\\$\\?[\\r\\n]+([0-9])");

edited Jul 23, 2015 at 7:36

answered Jul 23, 2015 at 7:23

Avinash Raj

175k32 gold badges247 silver badges289 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Avinash Raj Over a year ago

ya, ...\r called carriage return and \n newline char

SnowyCoder Over a year ago

so why you replaced it whit \\r?\\n ?

Avinash Raj Over a year ago

both would work. and also you don't need substring method for extracting the number.

Collectives™ on Stack Overflow

How can I find a digit after string with pattern?

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related