The following regular expression is found in a book I have been reading. It apparently can be used on an /etc/passwd file to find any accounts which have no password. I am having a heck of a time seeing how it works, and I was wondering if someone could run me through it. I will take a stab at what I think it is doing, and then maybe you could correct me where necessary...
Code:
grep '^[^:]*::'
Ok, so what I see here is 'Any line that begins with 0 or more characters that are *not* a colon, followed by two colons in a row. Now I would not have questioned my interpretation of the above except that the example in the book showed that such a grep would yield the following:
Code:
::0:0:::
Which seems to me to be a line that begins with 0 or more colons, which seems to be negated by the way I understand that regular expression. What am I missing?
I'm trying to get some exclusions into our sendmail regular expression for the K command. The following configuration & regex works:
LOCAL_CONFIG
#
Kcheckaddress regex -a@MATCH
+<@+?\.++?\.(us|info|to|br|bid|cn|ru)
LOCAL_RULESETS
SLocal_check_mail
# check address against various regex... (0 Replies)
I am not a big expert in regex and have just little understanding of that language.
Could you help me to understand the regular Perl expression:
^(?!if\b|else\b|while\b|)(?:+?\s+){1,6}(+\s*)\(*\) *?(?:^*;?+){0,10}\{
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This is regex to select functions from a C/C++ source and defined in... (2 Replies)
cat teledir.txt
jai sharma 25853670
chanchal singhvi 9831545629
anil aggarwal 9830263298
shyam saksena 23217847
lalit chowdury 26688726
If i use the below command , it is giving me the output with "," in between two name. how ? and also i would like to know the reason for the space used in... (1 Reply)
I have a file of protein sequences with headers (my source file). Based on a list of IDs (which are included in some of the headers), I'd like to print out only the specified sequences, with only the ID as header.
In other words, I'd like to search source.txt for the terms in IDs.txt, and print... (3 Replies)
I am having trouble parsing rpm filenames in a shell script.. I found a snippet of perl code that will perform the task but I really don't have time to rewrite the entire script in perl. I cannot for the life of me convert this code into something sed-friendly:
if ($rpm =~ /(*)-(*)-(*)\.(.*)/)... (1 Reply)
Ok, i've been trying to write some shell scripts. nothing challenging, but just automating
All of the tutorials i read say to start the file with
#!/bin/bash
or whatever your path to bash is.
So i do it, and all of my scripts error out saying ./nameofscript:command not found
when i... (4 Replies)
