Explanation of the (\((ALL|root)\))?:
The inner ( ) are for the | scope: ALL OR root.
Then there are the literal parens \( \) around it.
And then there are another ( ) around this for the ? scope: match zero or once.
Note that the greedy .* "match all" often matches too much.
guys,
my requirment goes like this:
I have a file, and wish to filter out records where
1. The first letter is o or O
and
2. The next 4 following letter should not be ther
I do not wish to use pipe and wish to do it in one shot.
The best expression I came up with is:
grep ^*... (10 Replies)
When i do ls -ld RT_BP* i am getting the following list.
drwxrwx--- 2 user group 256 Oct 17 10:09 RT_BP809
drwxrwx--- 2user group 256 Oct 17 10:09 RT_BP809.O
drwxrwx--- 2 user group 256 Oct 17 10:09 RT_BP810
drwxrwx--- 2user group 256 Oct... (2 Replies)
Hi, guys. I have one question, hope somebody can give me a hand
I have a file called passwd, the contents of it arebelow:
***********************
...
goldsimj:x:5008:200:
goldsij2:x:5009:200:
whitej:x:5010:201:
brownj:x:5011:202:
goldsij3:x:5012:204:
greyp:x:5013:203:
...... (6 Replies)
please can someone tell me what the following regrex means
grep "^aa*$" <file>
I thought this would match any word beginning with aa and ending with $, but it doesnt.
Thanks in advance
Calypso (7 Replies)
I have the following code:
ls -al /bin | tr -s ' ' | grep 'x'
ls -al: Lists all the files in a given director such as /bin
tr -s ' ': removes additional spaces between characters so that there is only one space
grep 'x': match all "x" characters that are followed by a whitespace.
I was... (3 Replies)
Hi,
I am executing a svnlook command to check to see if the following line exists. I need a regular expression to represent the line.
A /test/test1/qa/test2/index.html
A /test/test1/qa/test3/test.jpg
A /test/test1/qa/test3/test1.jpg
A /test/test1/qa/test4/test.swf
I just need to extract... (9 Replies)
Hi all,
How am I read a file, find the match regular expression and overwrite to the same files.
open DESTINATION_FILE, "<tmptravl.dat" or die "tmptravl.dat";
open NEW_DESTINATION_FILE, ">new_tmptravl.dat" or die "new_tmptravl.dat";
while (<DESTINATION_FILE>)
{
# print... (1 Reply)
i have a command line like this in csh script
grep -i "$argv$"
which i wanted to select the line ending with string provided as argument but it couldn't interpret the '$' (ending with)..
any help? (3 Replies)
Hi ,
I have few lines like
A20120101.ANU.ZIP
A20120401.ABC.ZIP
A20120105.KJK.ZIP
A20120809.JUG.ZIP
A20120101.MAT.ZIP
B20120301.ANU.XIP
I want to filter by
1. Files starting with A and Ending With Z ( ^A.*.ZIP$)
2. And either ANU, or KJK or MAT in the file name.
Hope my... (6 Replies)
Discussion started by: Anupam_Halder
6 Replies
LEARN ABOUT LINUX
sudo_root
sudo_root(8) System Manager's Manual sudo_root(8)NAME
sudo_root - How to run administrative commands
SYNOPSIS
sudo command
sudo -i
INTRODUCTION
By default, the password for the user "root" (the system administrator) is locked. This means you cannot login as root or use su. Instead,
the installer will set up sudo to allow the user that is created during install to run all administrative commands.
This means that in the terminal you can use sudo for commands that require root privileges. All programs in the menu will use a graphical
sudo to prompt for a password. When sudo asks for a password, it needs your password, this means that a root password is not needed.
To run a command which requires root privileges in a terminal, simply prepend sudo in front of it. To get an interactive root shell, use
sudo -i.
ALLOWING OTHER USERS TO RUN SUDO
By default, only the user who installed the system is permitted to run sudo. To add more administrators, i. e. users who can run sudo, you
have to add these users to the group 'admin' by doing one of the following steps:
* In a shell, do
sudo adduser username admin
* Use the graphical "Users & Groups" program in the "System settings" menu to add the new user to the admin group.
BENEFITS OF USING SUDO
The benefits of leaving root disabled by default include the following:
* Users do not have to remember an extra password, which they are likely to forget.
* The installer is able to ask fewer questions.
* It avoids the "I can do anything" interactive login by default - you will be prompted for a password before major changes can happen,
which should make you think about the consequences of what you are doing.
* Sudo adds a log entry of the command(s) run (in /var/log/auth.log).
* Every attacker trying to brute-force their way into your box will know it has an account named root and will try that first. What they do
not know is what the usernames of your other users are.
* Allows easy transfer for admin rights, in a short term or long term period, by adding and removing users from the admin group, while not
compromising the root account.
* sudo can be set up with a much more fine-grained security policy.
* On systems with more than one administrator using sudo avoids sharing a password amongst them.
DOWNSIDES OF USING SUDO
Although for desktops the benefits of using sudo are great, there are possible issues which need to be noted:
* Redirecting the output of commands run with sudo can be confusing at first. For instance consider
sudo ls > /root/somefile
will not work since it is the shell that tries to write to that file. You can use
ls | sudo tee /root/somefile
to get the behaviour you want.
* In a lot of office environments the ONLY local user on a system is root. All other users are imported using NSS techniques such as
nss-ldap. To setup a workstation, or fix it, in the case of a network failure where nss-ldap is broken, root is required. This tends to
leave the system unusable. An extra local user, or an enabled root password is needed here.
GOING BACK TO A TRADITIONAL ROOT ACCOUNT
This is not recommended!
To enable the root account (i.e. set a password) use:
sudo passwd root
Afterwards, edit the sudo configuration with sudo visudo and comment out the line
%admin ALL=(ALL) ALL
to disable sudo access to members of the admin group.
SEE ALSO sudo(8), https://wiki.ubuntu.com/RootSudo
February 8, 2006 sudo_root(8)