How to Use Shell Command to tar Directory Excluding Files/Folders?
Linux shell command “tar” supports the “–exclude” argument to exclude certain files/directories by placing them one after the other.
How to Create a Link to a Directory on Linux?
To create a link to a directory, use the “ln(link)” command followed by the “-s” flag at the current working directory or the user-choice location.
What Does set -e Mean in a Bash Script?
In a Bash script, the “set -e” identifies the error location and exits the script execution quickly without the execution of other commands.
How to Extract File Basename Without Path and Extension in Bash?
To extract file basename without path and extension, use the “basename” command. It can be done using the “parameter expansion” without the “basename.”
How to Concatenate String Variables in Bash?
The string variables can be easily concatenated by “placing them sequentially” and using the “+=” operator in Bash shell scripts.
How to Change Current Directory Using cd, pwd in Bash Script?
To change the dictionary in the current bash shell execute the script(bash) having the cd command with the “dot(.)” symbol and the “source” command.
How to Check if a Variable is set in Bash?
Bash provides the “-v”, “-z”, and “-n” options to check whether the variable is set or not, at the conditional statement of the “if-then-else-fi” loop.
How to Compare Two Files in Linux Terminal?
To compare two files in a Linux terminal, use the “diff(difference)” command, its supported “–color” flag for colorized output, and the “vimdiff” command.
How Does the “tail” Command’s “-f” Parameter Work?
The “-f(follow)” parameter of the “tail” command is mainly used by the system administrator for monitoring the text and log files in real-time.
How Do I Use grep to Show Only Filenames on Linux?
In Linux, the “grep” command allows the “-l(files-with-matches)” flag and the combination of the “find” command to show just filenames.
Difference Between Ctrl-Z and “&” in Bash Linux
The “Ctrl-Z” key and the “&(ampersand)” symbol are different on the basis of their “objectives”, “usage”, “implementation” and “states”.
How to Use Nested for Loop in Bash Shell?
Bash nested “for” loop contains the inner for loops that iterate entirely for each value of the outer for loop and execute the block of statements.
How to echo Shell Commands?
Linux bash scripting uses the “set -x” and “set -v” commands to echo the defined set of shell commands placed in it at any point.
How to Stop Docker in Linux?
To stop the Docker under Linux, utilize the “systemctl” and “service” command line manager with the “stop” utility. Follow the detailed procedure here
How to Restart PostgreSQL in Ubuntu?
To restart the “PostgreSQL” server in Ubuntu, use the “systemctl” and “service” command line managers with the “sudo” support in case of non-root users.
How to Create Desktop Shortcuts Using Ubuntu Terminal?
To create desktop shortcuts, copy an application’s “.desktop” file to the “~/Desktop.” Use the “ln” command in the terminal for the desktop file shortcut.
How to Customize GNOME in Ubuntu For a New Look?
To customize GNOME in Ubuntu, install the “Extension Manager” tool that provides many free and open-source extensions. Read this post for more details.
How to Install and Use ClamAV on Ubuntu 22.04?
The “ClamAV” CLI is installed from the Ubuntu standard repository via the “apt” and “ClamTK” GUI interface from the “Ubuntu Software” center.
Job Control Commands in Linux | bg, fg, and CTRL+Z
The “bg” places the foreground job in the background, and the “fg” resumes the background jobs. However, the “Ctrl+Z” key keeps the job in a “stopped” state.
What is $$ in Bash Shell Script?
In Linux, the bash shell variable “$$” returns the current bash shell process id that can be checked through the “echo” and the “ps(process)” commands.
How to Comment Out Multiple Lines at Once in Vim Editor?
To comment out multiple lines at once using the “vim” text editor “line number,” “regular expression,” and the “Visual Mode” feature properly.
How to Change, Replace, and Substitute in Vim?
The vim editor performs the change, replace, and substitute operation using the “Slash(\) and Dot(.)” operator, the “Substitute Command,” and “Line Number.”
How to Put a New Line Character? echo and Redirection Operator
To put a new line into a file using the echo command and redirection operator, use the “e” flag and separate each string by the special character “\n.”
How to Use ncdu to Check Disk Space in Linux?
The “ncdu” provides a command line interface to check the disk space details at the window’s bottom. For more details, follow this post.
How to Check the Package Version Using apt-get/aptitude?
To check the “install” package version, use the “apt-get” command with the “-s(simulation)” flag and the “aptitude” with the “version” flag.
Bash Indexed Array – Explained With Examples
The “Bash Indexed” array is a sequential arrangement of different types of elements associated with an “index,” a non-negative integer value.
How to Use Array in sh Script to Print All Values in Array?
To print all values of the array used in the sh script, utilize the “@” or “*” symbol at the indexed position. This task can also be done with the “for” loop.
How to Find the Device Driver Used for a Device in Linux?
To find the specific device drivers, use the “modinfo” command with the particular device name. For only the USB driver details, use the “lsusb” command.
Install and Use virt-manager in Ubuntu and Other Linux Distros?
In Ubuntu and other Linux distributions, the “virt-manager” can be installed simply from the local repository using default package managers.
How to Use split() with awk in Linux?
The “split()” is the “awk” command line function that splits the defined string into an “awk” array separated by the delimiter(default/user-choice).
Bash not Equal Operator for String Comparison
The “not equal” operator is the relational operator used to compare the two strings or the specified string. For more details, read this guide.
How to Edit Files on Ubuntu Command Line?
Ubuntu operating system supports a large list of command line text editors from which, most commonly, “nano” and “vim” are used to edit files.
Understanding a sed Command | sed ‘s/\s\s*/ /g’
In Linux, the sed Command: sed ‘s/\s\s*/ /g’ allows the users to replace more than one whitespace character or tab with a single whitespace globally.
What is $PWD in Linux?
The “$PWD” is an environment variable that contains the absolute path of the current working directory starting from the “root(\)” directory.
How to Argument String to Integer in Bash?
To convert the argument string to an integer using the “$((…))” arithmetic expansion operator, “expr,” “let,” “bc,” and “awk” commands in the bash script.
Bash Multiplication and Addition
In Linux, the bash addition and multiplication operations can be performed using the “arithmetic expansion,” “expr,” and the “let” command line utility.
What is the Difference Between Using bash and sh?
The “bash” and “sh” shells are different based on their “functionality,” “POSIX shell,” “programming language,” “compatibility,” and “command history.”
find’s “-exec rm {} \;” vs “-delete”
The “find” is the built-in command for finding files/directories based on their name, username, group, … Read More
What PDF Viewers are Available for Ubuntu?
Ubuntu supports “Evince”, “Zathura”, and “Atril”, PDF document viewers. These PDF viewers have simple interfaces alongside their unique functionalities.
How to Set Date and Time On Linux?
To set the manual date and time of the system, use the “date”, “timedatectl”, “hwclock”, and “ntpdate” commands and the “Date &Time” option via GUI.
What is LD_LIBRARY_PATH and How to Set the Environment Variable?
The “LD_LIBRARY_PATH” environment variable searches the directories of the shared libraries. It can also be set in Linux using the “export” command.
Where to Find sshd Logs in Linux?
The sshd Logs are stored in the “/var/log/auth.log” file. These log details can be displayed using the “grep”, “lastlog”, and the “journalctl” commands.
How to Replace Newline with Comma Using the `sed` Command?
To replace a “\n(newline)” to a “,(comma)” use the “sed” command “-z”, “H, h, d, x and y”, “-n, H, h, g, and p ”, “H, x, p”, and “a, b, $! and N” flags.
How to Create a Home Directory for Existing Users in Linux?
In Linux and its distributions, the user can easily create the home directory for an existing user with the help of the “mkdirhome_helper” command.
How to Sort Based on the Third Column?
In Linux, the “sort” command line utility is used with the “-k” flag to perform the sorting operation based on the third column.
How to Get the Execution Time of a Bash Script Effectively?
In Linux, use the “date”, “$SECONDS” internal bash variable, and the “TIMEFORMAT” string to get the execution time of the bash script.
What is the Difference Between daemon-reload and reload?
In Linux, the “daemon-reload” reloads the entire systemd unit files while the “reload” only reloads the specific service configuration files.
What are the Alternatives to Notepad++ on Ubuntu?
In Ubuntu, the alternatives to Notepad++ are “Nano”, “Gedit”, “Vim”, “Sublime text”, “Geany”, and “Kate”. Read this post for their detailed description.
What is the Purpose of the /var/lib/apt/lists Directory?
The “/var/lib/apt/lists” directory stores all the package information downloaded from the ubuntu server when the user runs the “sudo apt command”.
How to Trim Leading and Trailing Whitespace From the Output?
To trim the leading and trailing whitespaces from each line in the output of a file/script, use the Linux pre-installed “sed” and “awk” command line tools.
How to Sort Results From ls Command by Modification Date?
To sort the output of the “ls” command by modification date use its “-t” argument, and also the “-l(list)” flag that displays the “date&time” of the file/directory.
How to Set Custom Resolution Using xrandr?
In Linux, the pre-installed “xrandr” command offers the “newmode” and the “addmode” flags to set the custom resolution of the system monitor.
How to Count Total Number of Occurrences Using grep?
To count the total number of occurrences of the specified word/pattern, use the “grep” command with the “wc(word count)” and “tr(translates)” options.
How to Convert an epoch Timestamp to a Human Readable?
To convert epoch timestamp to human-readable format use the “date” command, “awk” having starftime format, and the “localtime()” with the “echo” command.
How to Color diff Output?
To color diff output use the “diff –color” command for the newer version of “diff” and the “colordiff” command line tool for the older versions.
How to Perform a Full Re-Installation of PIP and PIP3 on Ubuntu?
To reinstall the “pip3” for Python3 and “pip” for Python 2 use the default “apt” package manager with superuser privileges or log in as a root user.
How to Use apt clean, autoclean, autoremove? | Combined and Separately
In Ubuntu, the “clean”, “autoclean”, and “autoremove” commands clean up the system cache, additional dependencies, and outdated versions of packages.
How to Add New Lines When Using echo?
To add new lines, use the “-e(backspace interpreter)” and “$(bash variable)” with the “echo” command. An “echo” tool can also be used multiple times to do this.
How to Install the Latest cURL on Linux?
In Linux and its distributions, the “curl” can be installed via default package managers i.e “apt” (Ubuntu/Debian), “yum” (CentOS/RHEL), and “dnf” (Fedora).
How to Generate a Strong Password in Linux?
To generate a strong password, use the “urandom”, “makepasswd”, “gpg”, “apg”, “pwgen”, and “openssl rand” commands. It can also be done using the “Perl” script.
How to Update NodeJS Version in Ubuntu Command Line?
To update the NodeJs versions in Ubuntu, use the “NVM(Node Version Manager)”, “NPM(Node Package Manager)”, and “Binary Packages”.
What are SUID, SGID, and Sticky bits?
In Linux, SUID, SGID, and Sticky bit are permission bits that are utilized to specify special permission rules for the file or directory.
Difference Between “cd -” and “cd ~-” in Linux
The “cd -” and “cd ~-” jump into the recently used directory but the “cd -” also prints that directory’s absolute path in the terminal.
How to Loop Over the Lines of a File?
Use the “for” and “while” loops in the shell script to read the file content line by line. Both these loops provide simple syntax to perform this task easily.
How to Run a Shell Script in Background?
To run a shell script in the background, use the “&(ampersand)” bash control operator and the built-in “nohup” command line tool.
How to Create a Permanent Bash Alias?
To create a permanent bash alias, edit the “~/.bashrc” file in Linux. After that, reload it using the “source ~/.bashrc” command to activate newly alias.
Bash if Loop Examples (if then fi, if then elif fi, if then else fi)
In bash scripting, the “if” loop is used to execute multiple conditional statements using “if-then fi”, and “if then else fi” and “if then else if fi” loop.
What is the Meaning of exit 0, exit 1, and exit 2 in a Bash Script?
The “exit 0”, “exit 1”, and the “exit 2” returns the exit status of the bash shell script. The value of the exit command is stored in the “$(shell)” variable.
What is “declare” in Bash?
In Bash, the “declare” command sets the variable and functions alongside their attributes, “integer”, “string”, “array”, and “read-only” variables.
How to Restart the SSH Service?
Linux offers the “systemctl” and “service” commands to restart the “SSH” service instantly. It can also be restarted by accessing the “/etc/init.d” directory.
