The || represents a logical OR. The second command is executed only when the first command fails (returns a non-zero exit status). Here is another example of the same logical OR principle. You can use this logical AND and logical OR to write an if-then-else structure on the command line.
What does || mean in Linux?
|| means execute the statement which follows only if the preceding statement failed (returned a non-zero exit code).
What is || in shell script?
The OR Operator (||) is much like an ‘else’ statement in programming. The above operator allow you to execute second command only if the execution of first command fails, i.e., the exit status of first command is ‘1’.
What does && mean in bash?
“&&” is used to chain commands together, such that the next command is run if and only if the preceding command exited without errors (or, more accurately, exits with a return code of 0).
What does Operator do in Linux?
A way to control how tasks are executed or how input and output is redirected, can be done using operators. Although Linux Distributions provide a Graphical User Interface just like any other operating system, the ability to control the system via the command line interface (CLI) has many benefits.
What is && mean?
The logical AND ( && ) operator (logical conjunction) for a set of operands is true if and only if all of its operands are true. It is typically used with Boolean (logical) values.
What is the first line of shell script?
The first line of our script is called a shebang. It consists of a number sign and an exclamation point character (#!), followed by the full path to the interpreter such as /bin/csh. All scripts under Unix execute using the interpreter specified on a first line.
What is use of in shell script?
A shell script is a set of commands that, when executed, is used to perform some useful function(s) on Linux. … sh file, written by a user, contains all the commands used to perform a task so that we do not have to run those commands manually, one by one.
What is the difference between $* and $@ in Linux?
What’s the difference between $@ and $* [duplicate]
The $@ holds list of all arguments passed to the script. The $* holds list of all arguments passed to the script. … They appear to work the same in my scripts.
What are bash commands?
(source: pixabay.com) Bash (AKA Bourne Again Shell) is a type of interpreter that processes shell commands. A shell interpreter takes commands in plain text format and calls Operating System services to do something. For example, ls command lists the files and folders in a directory.
Which is command in Linux?
Linux which command is used to identify the location of a given executable that is executed when you type the executable name (command) in the terminal prompt. The command searches for the executable specified as an argument in the directories listed in the PATH environment variable.
How does grep work in Linux?
Grep is a Linux / Unix command-line tool used to search for a string of characters in a specified file. The text search pattern is called a regular expression. When it finds a match, it prints the line with the result. The grep command is handy when searching through large log files.
What is the use of redirection operator?
These allow you to control the input and output of your commands. They can appear anywhere within a simple command or may follow a command.