if is a command in Linux which is used to execute commands based on conditions. The ‘if COMMANDS’ list is executed. If its status is zero, then the ‘then COMMANDS’ list is executed.
What is in if condition in Linux?
Syntax. This code is just a series of if statements, where each if is part of the else clause of the previous statement. Here statement(s) are executed based on the true condition, if none of the condition is true then else block is executed.
What is if [- E in bash?
The “if –e” and “if –s” are such operators in Bash, used for testing the existence of a file. The difference between the two is that the former only tests the existence of a file, whereas the latter also checks if there are any contents in that file or not.
What does F mean in Linux?
Many Linux commands have an -f option, which stands for, you guessed it, force! Sometimes when you execute a command, it fails or prompts you for additional input. This may be an effort to protect the files you are trying to change or inform the user that a device is busy or a file already exists.
What does $? Mean in Linux?
$? -The exit status of the last command executed. $0 -The filename of the current script. $# -The number of arguments supplied to a script. $$ -The process number of the current shell. For shell scripts, this is the process ID under which they are executing.
What is if in bash script?
In bash scripting, as in the real world, ‘if’ is used to ask a question. The ‘if’ command will return a yes or no style answer and you can script the appropriate response.
What is set a bash?
set is a shell builtin, used to set and unset shell options and positional parameters. Without arguments, set will print all shell variables (both environment variables and variables in current session) sorted in current locale. You can also read bash documentation.
What is E Unix?
The ‘set’ command is used set and examine shell options, as well as set positional parameters. The -e flag does the following: -e Exit immediately if a command exits with a non-zero status.
How do I use find in Linux?
Basic Examples
- find . – name thisfile.txt. If you need to know how to find a file in Linux called thisfile. …
- find /home -name *.jpg. Look for all . jpg files in the /home and directories below it.
- find . – type f -empty. Look for an empty file inside the current directory.
- find /home -user randomperson-mtime 6 -iname “.db”
What does $FILE mean in Linux?
A text file (also referred to as a plain text file) is a file that contains only human-readable characters plus a few types of control characters, such as those used to indicate line breaks and tabs.
Why do we use Linux?
The Linux system is very stable and is not prone to crashes. The Linux OS runs exactly as fast as it did when first installed, even after several years. … Unlike Windows, you need not reboot a Linux server after every update or patch. Due to this, Linux has the highest number of servers running on the Internet.
What is Linux and why it is used?
Linux® is an open source operating system (OS). An operating system is the software that directly manages a system’s hardware and resources, like CPU, memory, and storage. The OS sits between applications and hardware and makes the connections between all of your software and the physical resources that do the work.
What is the use of $$ in Linux?
$$ is the id of the current process. Every process in a UNIX like operating system has a (temporarily) unique identifier, the PID. No two processes running at the same time can have the same PID, and $$ refers to the PID of the bash instance running the script.