Henry

Postfix is the mail transfer agent in Ubuntu that stores all records of the emails in the log file located under the directory “/var/log/mail.log”.

To show the DOSBox in full-screen mode, press the “Ctrl+F10” to lock the mouse and then “Left Alt+Enter” or make changes in the “dosbox-0.74-03.conf” File.

Yes, the “z” option with rsync speeds up the backup in specific scenarios depending on the factors like size, types of files, network, and CPU performance.

The “i686” packages run on processors having 32-bit compatibility while “x86_64” runs on processors having both 64-bit and 32-bit based compatibility.

To view all UUIDs for all available disks on the Linux operating system, use the “blkid”, “lsblk”, “ls”, “hwinfo”, “udevadm”, “tune2fs”, “dumpe2fs” commands.

In Linux, to know the number of CPU cores in a system considers the “proc/cpuinfo” file’s output or the “nproc”, “top”, “lscpu”, or “hwinfo” utility.

In Linux, the user can use the “nmap”, “netstat”, “netcat”, “/dev/tcp” or “lsof” tools as an alternative besides the “telnet” tool.

To exit from the tmux window, press the keyboard shortcut key “Ctrl+A” or “Ctrl+B” and then “D” or use the “exit”, “tmux detach” or “tmux kill-session” command.

To switch between multiple versions of Java, list the available versions and switch between them using the “sudo update-java-alternatives –set ” command.

To check the currently used DNS server, consider the “resolv.conf” file or built-in tools such as ”dig”, and “nslookup” or use the “Network” settings (GUI).

To copy a directory and its content to the new location, use the “cp” with the “R” flag, “rsync,” and ”tar” commands, or a GUI method.

In Linux, to check the hard disk performance of the system, the user can consider the utilities such as “hdparm”, “dd ”, “iostat”, or the “Disks” tool.

In Linux, To find the process ID of the process using the specific port, use the “netstat”, “ss”, “losf”, or the “fuser” utility.

To check the RAM size in the Linux, utilize the “/proc/meminfo file”, “free”, “top”, “vmstat”, “dmidecode”, “lshw”, or “hwinfo” utilities

To find and kill the zombie process on Linux, list down the zombie process, and send the SIGCHLD signal to its parent process.

To reduce the file size of the scanned PDF, use the command line utilities ghostscript (gs), and “ps2pdf” or utilize the PDF online compression tool.

The binary files in Linux are analyzed through the file, ldd, hexdump, strings, readelf, objdump, strace, ltrace, and xxd utilities.

In Linux, the easiest way to copy the SSH keys file to another machine is using the “ssh-copy-id” with the remote hostname.

In Linux, the terminal and shell environment are colorized using the ANSI color code, lolcat utility, or use the “preferences” option of the terminal.

In Linux, the sar is the command that is utilized for retrieving the report of the various system activities such as CPU utilization, memory utilization, etc.

To display the “top” command result sorted by memory usage, run the “top” in the terminal and press the “Shift + M” from the keyboard to sort it.

To add any user to the existing group, use the “userrmod” command with the syntax “sudo usermod -a -G [Group Name] [User Name]”.

The journalctl is the built-in utility to retrieve systemd logs with respect to time, service, boot-time, Kernel-related tasks, etc.

To use the OR condition in the grep command, specify the patterns separated with “\”, or use the Flags “E” or “e” in the given syntax.

To make the chown recursive, use the syntax “chown -R [Mode] [Directory/Path]” for changing the ownership, or “chown -R :[Gorup] [Directory/Path]” for the group.

The reason for the error is that the source path is not specified. To fix this error, specify the source path and copy the file recursively.

The reasons for this error are, either the root password is not set or the password is being entered incorrectly. To fix this, change/set the root password.

To save the output of the terminal into a file, three methods are utilized which are Redirection Operator, tee utility, or script method.

Linux is a Unix-like operating system because it works on the same design and principle as Unix, but it is not the exact implementation of Unix.

The TTY is a character-based device used as a medium for entering data, still a crucial part of the operating systems but in software form.

To cut the video with the “ffmpeg” tool, use the “ss” flag for the starting point and the “t” flag for specifying the ending point. For cropping, see the guide.

To use the gedit (GNOME Text Editor) command in Linux, open the terminal and type gedit with options and file name to edit the files.

To rsync a directory in Linux, use the “rsync” utility with the various options which depend upon the user’s requirements.

The cause of the bus error is the access to an invalid address, while the cause of the segmentation is the invalid access to valid memory.

To resolve this error, check if “policykit1” is installed. If it is not, then install it using the given command. Secondly, check the root privileges.

To fix this error, install the header “sudo apt install libpq-dev” or “sudo apt install ruby-dev” command in the terminal.

To get the hardware information in Linux, use the “hwinfo”, “lscpu”, “uname”, “free”, “top”, “lsblk”, lspci “lsscsi”, “inxi”, “lsusb” commands.

To force kill the screen session in Linux, use the “kill” option in the “screen -X -S [session_ID]” or the “quit” option to quit the whole session.

In Linux, to test if a port on a remote host is reachable or not, use the “nmap” tool, “telnet” service, or “nc” command in the terminal.

In Linux, to check the port is in the open state, use the “telnet”, “netcat(nc)”, “nmap”, “netstat” or “/dev/tcp” command.

In Linux, to list down the USB devices, use the “lsusb”, “dmesg”, “usb-devices”, “lsblk”, “df”, or “fdisk” utility in the terminal.

To remove the screen sessions, run the screen utility using the “r” flag with its session ID and then type exit or use the shortcut key “Ctrl+A+D”.

The reason for the error “gpg: keyserver receive failed: no name” is the problem with the keyserver that can be fixed by changing it to another server.

To fix this error, upgrade the pip to the latest version and install the missing libraries; the process and the commands are given in the article.

The reason for the error “importerror: libsm.so.6: cannot open shared object file” is the missing libraries that can be fixed by installing these libraries.