Parsing a syslog using Regex











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I am writing a Regex to parse a syslog entry. I am having challenges to able parse the entry until i hit "CMD". I would like all that appears after CMD to be grouped under (). Also, can you please provide suggestions to improve the regex



Here is my syslog entry:




Nov 21 23:17:01 ubuntu-xenial CRON[10299]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)




(<?month>[A-z]{3})s(<?date>[0-9]{2}?)s(<?time>[0-9]+:[0-9]+:[0-9]+)s(<?hostname>[a-z]+-[a-z]+)s(<?daemon>[A-Z]+)(<?pid>[[0-9]+]):s(<?user>([a-z]+))









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  • 1




    Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
    – simbabque
    Nov 22 at 17:11










  • "[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
    – Ramesh Rajan
    Nov 22 at 17:25










  • What happens when the day of the month has only a single digit?
    – Tim
    Nov 22 at 19:33















up vote
-1
down vote

favorite












I am writing a Regex to parse a syslog entry. I am having challenges to able parse the entry until i hit "CMD". I would like all that appears after CMD to be grouped under (). Also, can you please provide suggestions to improve the regex



Here is my syslog entry:




Nov 21 23:17:01 ubuntu-xenial CRON[10299]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)




(<?month>[A-z]{3})s(<?date>[0-9]{2}?)s(<?time>[0-9]+:[0-9]+:[0-9]+)s(<?hostname>[a-z]+-[a-z]+)s(<?daemon>[A-Z]+)(<?pid>[[0-9]+]):s(<?user>([a-z]+))









share|improve this question




















  • 1




    Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
    – simbabque
    Nov 22 at 17:11










  • "[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
    – Ramesh Rajan
    Nov 22 at 17:25










  • What happens when the day of the month has only a single digit?
    – Tim
    Nov 22 at 19:33













up vote
-1
down vote

favorite









up vote
-1
down vote

favorite











I am writing a Regex to parse a syslog entry. I am having challenges to able parse the entry until i hit "CMD". I would like all that appears after CMD to be grouped under (). Also, can you please provide suggestions to improve the regex



Here is my syslog entry:




Nov 21 23:17:01 ubuntu-xenial CRON[10299]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)




(<?month>[A-z]{3})s(<?date>[0-9]{2}?)s(<?time>[0-9]+:[0-9]+:[0-9]+)s(<?hostname>[a-z]+-[a-z]+)s(<?daemon>[A-Z]+)(<?pid>[[0-9]+]):s(<?user>([a-z]+))









share|improve this question















I am writing a Regex to parse a syslog entry. I am having challenges to able parse the entry until i hit "CMD". I would like all that appears after CMD to be grouped under (). Also, can you please provide suggestions to improve the regex



Here is my syslog entry:




Nov 21 23:17:01 ubuntu-xenial CRON[10299]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)




(<?month>[A-z]{3})s(<?date>[0-9]{2}?)s(<?time>[0-9]+:[0-9]+:[0-9]+)s(<?hostname>[a-z]+-[a-z]+)s(<?daemon>[A-Z]+)(<?pid>[[0-9]+]):s(<?user>([a-z]+))






regex perl regex-group






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edited Nov 23 at 5:31









James Z

11.1k71735




11.1k71735










asked Nov 22 at 16:55









Ramesh Rajan

32




32








  • 1




    Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
    – simbabque
    Nov 22 at 17:11










  • "[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
    – Ramesh Rajan
    Nov 22 at 17:25










  • What happens when the day of the month has only a single digit?
    – Tim
    Nov 22 at 19:33














  • 1




    Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
    – simbabque
    Nov 22 at 17:11










  • "[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
    – Ramesh Rajan
    Nov 22 at 17:25










  • What happens when the day of the month has only a single digit?
    – Tim
    Nov 22 at 19:33








1




1




Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
– simbabque
Nov 22 at 17:11




Your regex syntax is completely wrong. This can't work. Your named capture groups are wrong. It should be (<?name>[a-z]+), not [(<?name>)[a-z]+
– simbabque
Nov 22 at 17:11












"[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
– Ramesh Rajan
Nov 22 at 17:25




"[ ]" were added as i copied from an online parser. but the intent was (<?cpature-group>[a-z]+)
– Ramesh Rajan
Nov 22 at 17:25












What happens when the day of the month has only a single digit?
– Tim
Nov 22 at 19:33




What happens when the day of the month has only a single digit?
– Tim
Nov 22 at 19:33












1 Answer
1






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up vote
0
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accepted










Here's my revisions, with comments. In general, you might be better off making fewer assumptions about what the fields are going to contain. Here I'm using S which is "anything except whitespace". Furthermore, s+ will match some whitespace, whether that's just one character or more.



(<?month>S+)                    #
s+ # added + because single digit dates might have additional spaces
(<?date>[0-9]{1,2}) # changed {2}? to {1,2} because you might have one or two digits
s+ #
(<?time>[0-9]+:[0-9]+:[0-9]+) #
s+ #
(<?hostname>S+) # anything which isn't whitespace
s+ #
(<?daemon>S+) # just in case your daemon has a digit or lower case in its name
(<?pid>[[0-9]+]) #
: #
s+ #
((<?user>S+)) # your username might have digits in it; don't capture the brackets
s+ #
CMD #
s+ #
((<?command>.*)) # capture the command, not the brackets
s* # in case of trailing space
$ # match end of string





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    up vote
    0
    down vote



    accepted










    Here's my revisions, with comments. In general, you might be better off making fewer assumptions about what the fields are going to contain. Here I'm using S which is "anything except whitespace". Furthermore, s+ will match some whitespace, whether that's just one character or more.



    (<?month>S+)                    #
    s+ # added + because single digit dates might have additional spaces
    (<?date>[0-9]{1,2}) # changed {2}? to {1,2} because you might have one or two digits
    s+ #
    (<?time>[0-9]+:[0-9]+:[0-9]+) #
    s+ #
    (<?hostname>S+) # anything which isn't whitespace
    s+ #
    (<?daemon>S+) # just in case your daemon has a digit or lower case in its name
    (<?pid>[[0-9]+]) #
    : #
    s+ #
    ((<?user>S+)) # your username might have digits in it; don't capture the brackets
    s+ #
    CMD #
    s+ #
    ((<?command>.*)) # capture the command, not the brackets
    s* # in case of trailing space
    $ # match end of string





    share|improve this answer



























      up vote
      0
      down vote



      accepted










      Here's my revisions, with comments. In general, you might be better off making fewer assumptions about what the fields are going to contain. Here I'm using S which is "anything except whitespace". Furthermore, s+ will match some whitespace, whether that's just one character or more.



      (<?month>S+)                    #
      s+ # added + because single digit dates might have additional spaces
      (<?date>[0-9]{1,2}) # changed {2}? to {1,2} because you might have one or two digits
      s+ #
      (<?time>[0-9]+:[0-9]+:[0-9]+) #
      s+ #
      (<?hostname>S+) # anything which isn't whitespace
      s+ #
      (<?daemon>S+) # just in case your daemon has a digit or lower case in its name
      (<?pid>[[0-9]+]) #
      : #
      s+ #
      ((<?user>S+)) # your username might have digits in it; don't capture the brackets
      s+ #
      CMD #
      s+ #
      ((<?command>.*)) # capture the command, not the brackets
      s* # in case of trailing space
      $ # match end of string





      share|improve this answer

























        up vote
        0
        down vote



        accepted







        up vote
        0
        down vote



        accepted






        Here's my revisions, with comments. In general, you might be better off making fewer assumptions about what the fields are going to contain. Here I'm using S which is "anything except whitespace". Furthermore, s+ will match some whitespace, whether that's just one character or more.



        (<?month>S+)                    #
        s+ # added + because single digit dates might have additional spaces
        (<?date>[0-9]{1,2}) # changed {2}? to {1,2} because you might have one or two digits
        s+ #
        (<?time>[0-9]+:[0-9]+:[0-9]+) #
        s+ #
        (<?hostname>S+) # anything which isn't whitespace
        s+ #
        (<?daemon>S+) # just in case your daemon has a digit or lower case in its name
        (<?pid>[[0-9]+]) #
        : #
        s+ #
        ((<?user>S+)) # your username might have digits in it; don't capture the brackets
        s+ #
        CMD #
        s+ #
        ((<?command>.*)) # capture the command, not the brackets
        s* # in case of trailing space
        $ # match end of string





        share|improve this answer














        Here's my revisions, with comments. In general, you might be better off making fewer assumptions about what the fields are going to contain. Here I'm using S which is "anything except whitespace". Furthermore, s+ will match some whitespace, whether that's just one character or more.



        (<?month>S+)                    #
        s+ # added + because single digit dates might have additional spaces
        (<?date>[0-9]{1,2}) # changed {2}? to {1,2} because you might have one or two digits
        s+ #
        (<?time>[0-9]+:[0-9]+:[0-9]+) #
        s+ #
        (<?hostname>S+) # anything which isn't whitespace
        s+ #
        (<?daemon>S+) # just in case your daemon has a digit or lower case in its name
        (<?pid>[[0-9]+]) #
        : #
        s+ #
        ((<?user>S+)) # your username might have digits in it; don't capture the brackets
        s+ #
        CMD #
        s+ #
        ((<?command>.*)) # capture the command, not the brackets
        s* # in case of trailing space
        $ # match end of string






        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Nov 22 at 19:53

























        answered Nov 22 at 19:47









        Tim

        7,8512344




        7,8512344






























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