20 lines
1.1 KiB
Markdown
20 lines
1.1 KiB
Markdown
## Marking a script as executable
|
|
Sometimes, you may need to mark a script as an executable to run it. On Linux, this can be accomplished by `chmod +x [FILE]`, where `[FILE]` is the file you want to mark as executable. To unmark a file as executable, use `chmod -x`
|
|
|
|
## The Shebang
|
|
There are various shells with their own language syntax (`sh`, `bash`, `fish`, etc). Therefore, more complicated scripts will indicate a particular shell by specifying the absolute path to the interpreter as the first line, prefixed by `#!` like this:
|
|
```sh
|
|
#!/bin/sh
|
|
echo "Hello, World!"
|
|
```
|
|
`#!/bin/sh` means that this script can be executed by the binary located at `/bin/sh`, and so the reader knows this is a `sh`(ell) script.
|
|
|
|
## Variables
|
|
In bash, variable assignment is done with the `=` operator. Variables are conventionally named with `SCREAMING_SNAKE_CASE`, and can be accessed by prefixing the variable name with a dollar sign (`$`):
|
|
```bash
|
|
#!/bin/bash
|
|
# There may not be any spaces used during assignment, `A = B` means something different than `A=B`
|
|
# Assignment is done with the equal sign (=) operator:
|
|
MY_VARIABLE="Hi Mom!"
|
|
echo $MY_VARIABLE
|
|
``` |