Set startup script in ubuntu
Command for Startup of Ubuntu
Edit /etc/rc.local and add your commands
The script must be ends with "exit 0"
Command for Rebooting Ubuntu
Put your script in /etc/rc0.d
Make it runable (sudo chmod +x myscript)
The name of your script must begin with K99 and run at the right time.
LVM find physical disk of a filesystem
Sometimes we will be in a situation to find which physical disk are used by a filesystem? Now a days servers are configured with lvm by default. you can use below command to find the physical disks used by a filesytem.
# lvs -o +devices /dev/mapper/VG_Name
# lvs -o +devices ..
How to protect servers against heartbleed bug
What is heartbleed?
The Heartbleed bug concerns a security vulnerability in a component of recent versions of OpenSSL. OpenSSL cryptographic software library is a technology used by more number of websites or servers for secure the traffic, passwords and other sensitive information transmitted to and from users and visitors.
There is a ..
Proftp client does not timeout
Normally in proftd when mod_tls is enabled, sometime user might face issue with ftp connection, There might be error like aborting transfer: Link to file server lost
TLSRenegotiate [ [\"ctrl\" secs] [\"data\" Kbytes] [\"timeout\" secs]|[\"required\" on|off]|\"none\"]
Default TLS connection setup
TLSRenegotiate ctrl 3600 data 512000 required off timeout ..
Linux create core dumps for processes
How to create core dumps for processes on Linux Operating System?
Core dumps can be enabled or disabled in linux operating system by using below techniques. There is a default entry as below in /etc/profile to disable core dumps. To enable the core dumps you have to modify the given line ..
Enable log reporting for sftp server
Normally when we use FTP server which in default has configuration for log reporting. When we use sftp which use open-ssh for file transfer the log reporting can be configured as below.
How to configure log reporting for SFP in linux server? This works for openssh-server-4.3 or above.
# vi ..
How to find fiber card links are up or down
systool is linux command which is used to view system device information by bus, class, and topology.
Get simple information about the Fibre Channel HBAs in a machine:
# systool -c fc_host -v
Get verbose information regarding the SCSI adapters present on a system:
# systool -c scsi_host -v
See what Fibre Channel ..
How to use ssh-agent and ssh-add
How to create login with no password ssh-agent?
what is ssh-agent?
ssh-agent is a background program that handles passwords for SSH private keys
What is ssh-add?
The ssh-add command prompts the user for a private key password and adds it to the list maintained by ssh-agent. Once you add a password to ssh-agent, you ..
How to find server serial number make and model
How to find server serial number make and model?
How do you search for hardware information on a server? In linux dmidecode is a command which is used to find hardware info of a server. When there is necessity to find server make and model you can use the dmidecode to ..
Find files in directory and change permission
How to change permission for only files in directory?
How to list only files in directory?
The below command will list only files and not direcrories in the folder.
# ls -l | grep -v \'drwx\'
This will help to list only files and change permission for files. this can be done by ..
Maximum number of users on Linux
What is the maximum number of users can be created on Linux?
How many users can be created on Linux?
The 2.6 Linux kernel supports up to 4,294,967,296 user IDs.
The 2.4 kernel only supports 65,536.
Ftp command shows GMT
When I am going to put a file in a server ftp client is showing in GMT while sytem clock is showing IST. When we use the ftp command or ftp client to connect to a Linux server, the files modification time shown is different from the time shown in ..
Trick to enable dmesg time stamps at boot time
How to Enable dmesg time stamps at boot time
In Linux OS user startup scripts can be added in /etc/rc.d/rc.local. As a best practice, it is recommended to create a separate start-up script /etc/rc.d/rc.local.user to separate Linux OS initialization commands from user-defined commands.
Check whether the /etc/rc.d/rc.local start-up script contains the ..
Enable timestamp for dmesg logs
Logs that are written into dmesg kernel ring buffer do not have time stamp by default. For troubleshooting purposes, it can be helpful to have time stamps for logs that are written into dmesg kernel ring buffer.
Follow the below steps to enable timestamp in dmesg log, Enable dmesg timestamp ..
How does time stamp calculated in linux
In Linux OS time stamps are printed in \"seconds since boot\". The system uptime can be helpful to calculate an absolute time stamp if needed (run the uptime command).
The algorithm below is demonstrated on the example given above:
[196149.728085] wlan0: authenticated
Take the logs time stamp in seconds: