Basic commands used on linux terminal part 9


This is a basic Linux command list or cheat sheet for the beginners. Those who are trying to learn Linux commands this is for them. this is the part nine for the beginners.

  1. Iptables/firewalld – this is a very powerful tool on Linux. It is used for traffic control and packet management. We can set rules on different ports and IPs. There are verities of work can be done by this tool. It can be used as a firewall too. All we need to do is to find the requirements to put the rule.
    example: iptables [options] arguments or firewalld-cmd [options] arguments
  2. Lsmod – this tool is used to find the modules that are using by the kernel. It is a very important tool to maintain the processes of the operating system. The modules are used for activating a particular hardware or process, this command can show the last module used and what the process it is activating which system. This command shows the exact output of /proc/modules.
    example: lsmod
  3. Curl – it is used for transferring data. It is supported by different protocols like ftp, http, scp, telnet etc. it have some important features with it. This command can show the process bar for an active transfer. Also we can use proxy, user authentication, ftp uploading and lot more. It has few options that can help a user in to maintain a proper file transfer over network.
    example: curl protocol://url
  4. Strace – this is a very powerful tool to trace any kind of activity in system. It can find any system call from any process worked on the processor. We can record the output in a file. Also it can help for forensic report generation. It has some powerful options to find a particular process using system name, process ID or even a process.
    example: strace [option] argument
  5. Od – this tool’s full form is octal dump. A command with the ability to represent in different mathematical forms. It usually represents the content of a file in octal format. But we also can show a file in binary, hexadecimal and ACSII. This command is used for debugging files. But the files output is not human readable.
    example: od [option] file
  6. Nc – netcat is the full form of this command. This tool is used for network monitoring. It can monitor all kind of protocols both tcp and udp. This tool can be used as simple TCP proxy, network daemon testing and many more network related exploration works. A very powerful tool for network maintenance. We can redirect the result into a file from this tool.
    example: nc [option] argument
  7. Mailq – this is a tool related with email service. Used by several email daemons. Mailq shows the emails that are being queued to process. As long the mail is not being cleared from the queue we can get a report of the emails we have in the queue. It is a very useful command for email server administrators.
    example: mailq
  8. Postsuper – this is also an email maintenance tool for email server administrator. This tool can be used by only root or other super users. This tool can delete a queued mail or it can reverse the mail to the queue. It also can handle other mail related directories like incoming, active, deferred, bounce, defer, trace and flush.
    example: postsuper [option] argument
  9. Postqueue – this command is used for maintaining mail queue for linux sendmail service. Super user privilege is required to use this tool. This tool is used for reporting the present queue and re queue the deferred mail. Also we can flush the whole queue using this tool.
    example: postqueue [option]
  10. Postconf – this command is used for displaying the parameter of postfix configuration. It also shows the parameter changes with error reporting. This command has various parameters to show the particular information. This tool is all about postfix service.
    example: postconf [option] postfix configuration directory

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