Linux
Usermod change existing home directory
You can alter user account information by editing /etc/passwd file.
# vi /etc/passwd
You can change the users home directory in the /etc/passwd file and copy the files to new location.
It is recommended that you use usermod to avoid any syntax errors:
usermod : Utility to modify existing user ..
How to use unrar and rar in linux
Here I will show you how to extract .rar files in linux
For extracting rar files in linux first you have to install rar in linux.
Follow the below steps to rar install linux.
In Redhat or Fedora core Linux:
# yum install unrar
In Debian Linux, use apt-get as follows to install ..
Override the overwriting while copying
In linux operating system when you try to copy files from one directory to another directory, the cp(copy) command will ask for overwriting if the file already exists.
Even if you use force option it will ask for overwriting. you can get out of this problem by two ways.
1) Use unalias
..
Find the process name using process id
How can I find the process name from the process id?
You can find the process name or the command used by the process-id or pid from
/proc/pid/cmdline
For exmaple:
# ps aux
................
................
user 2480 0.0 1.2 119100 12728 ..
Find mail queue in sendmail
The below command's helps you after configuring the sendmail.
ExamplesWhat it doessendmail -bp or mailqDisplays the status of the mail queue. List Email files waiting to be sent and incoming.ps ax | grep sendmailLists the process status of the sendmail daemon. May display something like....... sendmail: accepting connections on port ..
Increse the semaphores
To increase or set the semaphores follow the bellow steps.
To list the semaphores use the command ipcs
[localhost/]# ipcs -ls
------ Semaphore Limits --------
max number of arrays = 128
max semaphores per array = 250
max semaphores system wide = 32000
max ops per semop call = 32
semaphore max value = 32767
To change semaphore setting ..
Install VLV Mulrimedia player with firefox plugin
How to install vlc plugin with firefox browser?
To install the vlc plug into the firefox browser in linux follow the below steps.
Redhat / Fedora users: login as root / su user and run the command
yum install vlc vlc-plugin-* mozilla-plugin-vlc
ubuntu uses execute the below command
sudo apt-get install vlc vlc-plugin-* mozilla-plugin-vlc
This ..
Vim remove ^v char
How to remove ^v characters in vi / vim ediitor?
To remove control V / ^v characters in vi editor follow the below steps
:%s/^v//g
Type as below step by step:
step 1:- :
step 2:- %s
step 3:- /
step 4:- control+v or ctrl+v
step 5:- /
step 6:- /g
where,
%s ..
Create user with comment and home directory
To create a user by specifying different home directory and by specifying the user details with his name and other details use the below command.
Syntax:
useradd -m -d <home directory> -u <user-Id> -s <shell> -c "<comment on user/details>" <username>
Example:
useradd -m -d /data/home/admin -u 555 -s /bin/bash -c "W3calculator Admin" admin
Where,
-d ..
Usermod command to change group
By default a user is created with the same group name. You can change the group of a user to another group as specified in the above example.
syntax:
usermod -g <groupname> -U <username>
You can change the group of a user by using the usermod command.
example:
usermod -g newgroup -U myuser
usermod -g ..
How to build a website
How to create a Website?
Creating a website is much easier. Just three basic steps are to be followed to
create your own website.
1) Register your Domain name.
2) Find a Web Host.
3) Build your site.
Registering your Domain name
A domain name is the thing that looks like this: "yourdomain.com". Your domain
name ..
Too many open files java io FileNotFoundException
When you receive the error java.io.FileNotFoundException(Too many files open) follow the steps given below to fix the error.
Set User Level File Descriptors Limit(FD):
you can limit tomcat(or any other users) user to specific limits by editing /etc/security/limits.conf file, enter
# vi /etc/security/limits.conf
Set tomcat user soft and hard limits as follows:
tomcat soft nofile ..
How to find total php-cgi size
Here is how you can find out total httpd and php-cgi size:
ps -aylC php-cgi | grep php-cgi | awk '{total += $8}END{size= total / 1024;
printf "Total size in mb: %.2f\n", size}'
And for httpd:
ps -aylC httpd | grep httpd | awk '{total += $8}END{size= total / 1024;
printf "Total ..
Kill a users process
Te below command will kill the process of a particular user
kill -9 `ps -u w3calculator -o "pid="`
..
Update clamv antivirus database
Try running freshclam as root. You can also daemonize it to automatically check after specified time. Look for /etc/freshclam.conf file that has all the settings for it.
To daemonize it,
freshclam -d
The below command to schedule the update of clamav antivirus database
crontab -e (make sure you run this command as root)
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