What does #! mean in COMPUTING
#! is an abbreviation for "shebang". This term originated in the computing world to refer to a special type of comment line at the beginning of code written in assembly language. The #! comment was used to signify that the file was an executable program, rather than just data. This allowed programs to be run directly from disk without having to go through a complicated loading process. Today, it's still used as a special comment marker and is often seen at the start of many scripts written in Unix-like operating systems such as Linux and BSD.
#! meaning in Computing in Computing
#! mostly used in an acronym Computing in Category Computing that means Shebang
Shorthand: #!,
Full Form: Shebang
For more information of "Shebang", see the section below.
Meaning
The most common use of #! in computing today is as a “shebang” – or “sharp bang” – line at the beginning of a script file, which tells the system what interpreter should be used to execute it. In addition to this, some programming languages such as Python use #! as part of their syntax so that they can be identified by other programs more easily. It can also be used as a prefix for certain commands entered into a command shell for quick execution.
Full Form
The full form of #! is "Shebang". This term originated from the days when computers used assembly language for writing code, and #! signaled that what followed was an executable program instead of data or comments. Nowadays, #! has become synonymous with scripting and is generally used by systems like Linux and BSD to denote a script file instead of plain text.
Essential Questions and Answers on Shebang in "COMPUTING»COMPUTING"
What is a Shebang?
A shebang is the name given to the character sequence consisting of the characters number sign and exclamation mark (#!) at the begining of a script. It informs unix-like operating systems that this file is a shell script and that it should be run by typing in /bin/sh followed by the path of the file.
What are the benefits of using a Shebang?
By using a shebang, you can ensure that your script files are automatically executed with specific permissions and environment variables set by the command or interpreter specified in the shebang. This can help ensure that your scripts have all necessary access permissions, as well as any specific special environment vars for execution.
How do I create a Shebang line?
A shebang line is created using the following syntax #!. The # (number sign) must start off the line, followed immediately after with an exclamation point (!). After this, you will specify what command or interpreter you want to use. For example, #!/bin/bash will tell your machine to use Bash when running this file as a script.
Does my Shebang need to execute if I am only running my script on one system?
A shebang is not absolutely required for running scripts on a single system, but it does make life easier for users who may be unfamiliar with scripting commands in different systems since they can quickly adapt their scripts to different systems without needing to learn new commands.
What happens if I forget my Shebang line?
If you do not include a shebang line in your script, then your machine will attempt to interpret it based on its own settings; which could lead to errors or unexpected behavior within your program. In other words, without a shebang, there's no guarantee that your commands will be interpreted correctly or even at all.
When should I use multiple interpreters with Shebangs?
You might want to consider having multiple interpreters in your code if you plan on running your script across multiple platforms where different interpreters are used in each platform (i.e Windows OS vs Linux). In these cases having multiple interpreters allows you to maintain compatibility regardless of what system you’re running on.
What programming language supports Shebangs?
Generally any language which uses UNIX style executables can support Shebangs, such as Bourne Shell Scripts (sh), Perl Scripts (.pl), Python Scripts (.py), Ruby Scripts (.rb), etc...
Is there anything else I should know about creating Shebangs?
It’s important to remember when creating shebangs that they must always begin with either ‘#!’ or ‘//!’ followed by an executable path (such as /bin/bash). This ensures that whatever command or interpreter follows after those two characters is executed when running this file as a script.
Final Words:
In summary, the abbreviation #! stands for "shebang" and has its roots in early computing terminology when files were written in assembly language. Nowadays it is mostly associated with scripting files for Unix-like operating systems such as Linux or BSD but can also have different functions depending on what programming language you are working with.