Login or Register to Ask a Question and Join Our Community


Shell Programming and Scripting

help with simple regex expression

Login to Discuss or Reply to this Discussion in Our Community

 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting help with simple regex expression
# 1  
Old 12-16-2010
help with simple regex expression
I am trying to grep the following line in a file using a bash shell:

(..)
admin1::14959::::::
(..)

It works with the following expression (as expected)

# cat file | grep ^[a-z0-9]*::
admin1::14959::::::

but it does not work with (not expected)

# cat /etc/shadow | grep ^[a-z0-9]+::

I assume the difference is the + vs. the *. According my
understanding the * matches the preceding character 0 or
more times and the + matches the preceding character 1
or more times. Therefore, the match should be in both cases
"admin1::"

I can not see my mistake. Any ideas ?
# 2  
Old 12-16-2010
That's an extended regexp. Use grep -E.
This User Gave Thanks to verdepollo For This Post:
schms
# 3  
Old 12-16-2010
Or # cat /etc/shadow | egrep ^[a-z0-9]+::

Or # cat /etc/shadow | grep ^[a-z0-9][a-z0-9]*::
This User Gave Thanks to Chubler_XL For This Post:
schms
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. UNIX for Beginners Questions & Answers

Sed: -e expression #1, char 20: unterminated address regex

I am trying to add word in last of particular line. the same command syntex is running on prompt. but in bash script give error."sed: -e expression #1, char 20: unterminated address regex" Please help. for i in `cat servername`; do ssh -q -t root@$i sed -i '/simple_allow_groups =/s/$/,... (4 Replies)
Discussion started by: yash_message
4 Replies

2. UNIX for Beginners Questions & Answers

Regex Expression Replace

I have a XML file where there is a tag with like <wd:address_line_1>1234 Street</wd:address_line_1> I want to replace the values "1234 Street" with "Test Data". Different people have different address lines and i want to replace with a fixed value to mask the file. I was trying to use sed... (7 Replies)
Discussion started by: dr46014
7 Replies

3. Shell Programming and Scripting

awk regex expression works in AIX but not in Linux

I have following expression: echo "Sun 12 Jul BST 2014\nSun 12 Jul 2014\nSun 12 Jul IS 2014" | awk '/(Sun)+( 12)+( Jul )+({3} )?(2014)/{print;}' I ran above code in AIX box and output is as follows Sun 12 Jul BST 2014 Sun 12 Jul 2014 I ran above code in Linux box and output is as... (8 Replies)
Discussion started by: kamlesh_pradhan
8 Replies

4. Shell Programming and Scripting

Hi im new to bash scripting I want to know what does the regex expression do ??

# check host value regex='^(||1|2|25)(\.(||1|2|25)){3}$' if ')" != "" ]; then if ]; then echo host $host not found exit 4 fi elif ]; then echo $host is an invalid host address exit 5 fi (1 Reply)
Discussion started by: kevin298
1 Replies

5. Emergency UNIX and Linux Support

Regular expression (regex) clean up text

Hi, Server - MEDIAWIKI - MYSQL - CENTOS 5 - PHP5 I have a database import of close to a million pages into my wiki, mediawiki site, the format that were left with is not pretty, and I need to find a way to clean this up and present it nicely... I think regex is the best option as I can... (1 Reply)
Discussion started by: lawstudent
1 Replies

6. Shell Programming and Scripting

awk variables in regex expression ?

Hello, Could someone explain why this one returns nothing: $ x=/jon/ $ echo jon | awk -v xa=$x '$1~xa {print}' $ while the following works fine: $ x=jon $ echo jon | awk -v xa=$x '$1==xa {print}' $ jon and the following works fine: $ echo jon | awk '$1~/jon/ {print}' $ jon ... (3 Replies)
Discussion started by: vilius
3 Replies

7. Shell Programming and Scripting

Creating a regex expression

Good morning all!! In my code I and looking through file /etc/syslog.congf and printing every line that has /var/log in it. I need to turn the if 9$line) into a regex code instead. #!/usr/bin/perl @file= 'cat /etc/syslog.conf'; //when foreach $line (@file){ if ($line =~... (3 Replies)
Discussion started by: bigben1220
3 Replies

8. UNIX for Advanced & Expert Users

Regular expression / regex substition on Unicode text

I have a large file encoded in Unicode that I need to convert to CSV. In general, I know how to do this by regular expression substitutions using sed or Perl, but one problem I am having is that I need to put a quotation mark at the end of each line to protect the last field. The usual regex... (1 Reply)
Discussion started by: thomas.hedden
1 Replies

9. Shell Programming and Scripting

Regular expression (regex) required

I want to block all special characters except alphanumerics.. and "."(dot ) character currently am using // I want to even block only single dot or multiple dots.. ex: . or .............. should be blocked. please provide me the reg ex. ---------- Post updated at 05:11 AM... (10 Replies)
Discussion started by: shams11
10 Replies

10. Shell Programming and Scripting

Replace if regex on specific column matches expression?

I am attempting to convert rewrite rules to Nginx, and since due to the mass amount of rewrites we must convert, I've been trying to write a script to help me on a specific part, easily. So far I have this: rewrite ^action/static/(+)/$ staticPage.php?pg=$1&%$query_string; What I want done... (5 Replies)
Discussion started by: EXT3FSCK
5 Replies
Login or Register to Ask a Question