- find – this command is a complex command for any beginner. But it is one of the very important commands we need to learn. Because we will find this command very useful on almost every time we work on troubleshooting. It has so many different ways to show output. Also we may use this command to find and execute some other commands on the found files through this command. We use this command with various nested commands in it when it is necessary.
example: find [option] argument
- Free – this command used to see the memory status. We can get the report just by this command without any parameter. But it does have few parameters to get the report as you want. It shows the system memory, swap memory and buffer. This is a frequently used command for system administrators.
example: free –m
- Mount – mount command is used for mounting a storage device or a file system. As this works with only storage or file system so it needs to be specified the file system type most of the times. If the system file system and the file system of the newly added storage are same only then it is okay to mount without mentioning the file system. Also for mounting a device we need to mention the device name and the mount point.
example: mount [option] devicename mountpoint
- Umount – this command is used to un mount the device whenever necessary. Most of the time it is used for maintenance reasons. When we need to maintenance the storage of the system then we have to un mount the hard disk and set new one or the previous one.
example: umount [option ] devicename
- Setup/nmtui – setup and nmtui are both network configuration tools for centos. Setup usually used on centos 6 and nmtui is used on centos 7. We can use setup on centos 7 too if we install a certain package. It has some very extensive manipulation workarounds using these tools.
example: setup / nmtui
- Route – this command is used to show and set routing table. Just route command will show the routing table existing on the system. By using n parameter we can mention the number of routing path we want to see. Also we can declare default routing path for different networks. This is a very useful tool for both routing and maintaining a network.
example: route –n
- Traceroute – traceroute is a route tracking tool. It sends a sample packet to find the route that a packet uses and reports back to the system. It is a very useful tool to communicate and troubleshoot to maintain a particular path for the packet routing. It is very necessary when it is about email server or file transfer server.
example: tracroute ip-address
- Wget – wget means “web get”. This is a very commonly used in Linux in case of downloading any kind of file from internet. We can download file or even folders from internet or any network. For using this command we need to have the location or link of the file as an argument.
example: wget (the link of the file)
- Dig – this command is a very useful command for so many reasons. It is used to find a domain’s all kind of record. We can find the A record also the AAA record and the MX entry too. So when we need to know the details about a domain or DNS record we use this command with a domain as argument.
example: dig example.com
- Yum – yellowdog updater modified. This command is used for install, update, remove and finding other packages. This is a very important tool for centos and red hat Linux. This is a open source tool for package management. We need to use it for update regularly. Yum repositories for all kind of work.
example: yum [option] packagename