Commands tagged shell

Thanks to comment if that works or not...

If you have already typed that snippet or you know you already have IO::Interface::Simple perl module, you can type only the last command :

( The first perl command will install the module if it's not there already... )

Exit with error if script is not run in a terminal

If your script needs to be run in a terminal, this line at the top will stop it running if you absent-mindedly double-click the icon, perhaps intending to edit it. (Of course this won't help with scripts that run in the background.)

Usage:

I often need to cd where no man wants to go (i.e. long path). by enabling the shell option cdable_vars, I can tell cd to assume the destination is the name of a variable.

Initialized empty Git repository in /home/user/path/to/dir/.git/

Useful in while and if statements

Remove everything in current directory except files starting with "ca".

Works in all shells. Does not require a test. Handles like an assertion.

Also searches for aliases and shell builtins

Searches in order of the directories of $PATH. Stops after finding the entry; looks for only that fileName. Works in Bourne, Korn, Bash and Z shells.

Manages everything through one sed script instead of pipes of greps and awks. Quoting of shell variables is generally easier within a sed script.

rkhunter (Rootkit Hunter) is a Unix-based tool that scans for rootkits, backdoors and possible local exploits. rkhunter is a shell script which carries out various checks on the local system to try and detect known rootkits and malware. It also performs checks to see if commands have been modified, if the system startup files have been modified, and various checks on the network interfaces, including checks for listening applications.

chkrootkit is a tool to locally check for signs of a rootkit,Get it from the website http://www.chkrootkit.org

To get information at your fingertips about Apache compilation.

Like many other thing in Linux ,you can see the same thing in different way.

This is a handy way to find which modules are loaded with Apache web server.

This command will reveal login has been made to the system as well as when the reboot occurs. It uses a file called /var/log/wtmp,which captures all the information about the successful login and reboot information. It has many switch ,by which you can get an idea when people login how long they stay.

This is wonderful perl script to check the web server security and vulnerability .Get it from here :http://www.cirt.net/nikto2

Here are some key features of "Nikto":

? Uses rfp's LibWhisker as a base for all network funtionality

? Main scan database in CSV format for easy updates

? Determines "OK" vs "NOT FOUND" responses for each server, if possible

? Determines CGI directories for each server, if possible

? Switch HTTP versions as needed so that the server understands requests properly

? SSL Support (Unix with OpenSSL or maybe Windows with ActiveState's Perl/NetSSL)

? Output to file in plain text, HTML or CSV

? Generic and "server type" specific checks

? Plugin support (standard PERL)

? Checks for outdated server software

? Proxy support (with authentication)

? Host authentication (Basic)

? Watches for "bogus" OK responses

? Attempts to perform educated guesses for Authentication realms

? Captures/prints any Cookies received

? Mutate mode to "go fishing" on web servers for odd items

? Builds Mutate checks based on robots.txt entries (if present)

? Scan multiple ports on a target to find web servers (can integrate nmap for speed, if available)

? Multiple IDS evasion techniques

? Users can add a custom scan database

? Supports automatic code/check updates (with web access)

? Multiple host/port scanning (scan list files)

? Username guessing plugin via the cgiwrap program and Apache ~user methods

Sometime you need to run firefox from the command just to rectify something about it.Means,if some of the addon broke you firefox setting or theme broke your ff setting then fall back to commandline i.e shell and type the mentioned command. It will open up an information box with few option along with the checkbox besides them(means you can select them) to start the web browser in safe mode.Besically deactivating all the addon and theme,except the default one.Once you are done/rectified thing ..close that session and reopen the browser normally.It should work.

Once it is connected to the remote server by that ssh protocol,the mentioned command will start working on that server.

If you follow my other posting regarding "vipw" and "vigr' then no explanation required.It has done the same thing as did with those two command.Open the /etc/sudoers file and attach a lock with it. Once you are done with it ,the lock gets released and the changes reflected to the original file.It will open a tmp file in vi editor to give you the chance to edit the sudoers file securely.visudo parses the sudoers file after the edit and will not save the changes if there is a syntax error. Upon finding an error, visudo will print a message stating the line number(s) where the error occurred and the user will receive the "What now?" prompt. At this point the user may enter "e" to re-edit the sudoers file, "x" to exit without saving the changes, or "Q" to quit and save changes. The "Q" option should be used with extreme care because if visudo believes there to be a parse error, so will sudo and no one will be able to sudo again until the error is fixed. If "e" is typed to edit the sudoers file after a parse error has been detected, the cursor will be placed on the line where the error occurred (if the editor supports this feature).

PS: Although I have had experienced myself and few people shown to me that it behaves badly in some distribution ,noteably SLES.But the problem can be rectified with little caution.

If you follow my previous posting regarding "vipw" then no explanation required.The same method goes behind this command also.It will open an tmp file in vi editor to give you the enlisting to edit the group file.And most importantly to attach a lock with it.Once you are done ,the lock is released and the changed reflected to the original file.So you can securely edit the group file over the network without the fear of being tampered .

Now a bit of explanation required for this command.Once you type the command it opens up an vi editor with an temporary file enlisting the password file information .So if you make an change it will not reflected in the passwd file until you save the file.The reason behind using this command over other way to view the password file in network environment is that it locks the password file when you start working with it.So no one can temper with it during that period.Once you are done(means you save the tmp file) ,it will release the lock associated with it.I think it's a better mechanism to view the sensitive data like passwd file.Never ever use other tool like cat, nano or any other means.

After you install slocate ,the first thing you have to do with it to initialise the database by issuing a command " slocate -u" . And then onwards just give the filename or dirname as a argument to the slocate command will reveal the files/dirs location in the system along with path.Moreover over it's an securely way of looking into the file system.