trude/web
1
0
Fork 0
mirror of https://github.com/TrudeEH/web.git synced 2025-12-06 00:13:36 +00:00
Code Issues Packages Projects Releases Wiki Activity

Use dash for scripts instead of bash; Fix typo

Browse Source
This commit is contained in:
TrudeEH
2025-04-23 15:09:15 +01:00
parent 39fc764344
commit f12f6ce973
3 changed files with 25 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
content/.obsidian/workspace.json vendored
View File

@@ -14,12 +14,12 @@
"state": { "state": {
"type": "markdown", "type": "markdown",
"state": { "state": {
"file": "drafts/bash.md", "file": "notes/firewall.md",
"mode": "source", "mode": "source",
"source": false "source": false
}, },
"icon": "lucide-file", "icon": "lucide-file",
"title": "bash" "title": "firewall"
} }
} }
] ]
@@ -218,13 +218,14 @@
}, },
"active": "b1ce9fc55dcb67b6", "active": "b1ce9fc55dcb67b6",
"lastOpenFiles": [ "lastOpenFiles": [
"Pasted image 20250422121610.png", "notes/firewall.md",
"drafts/bash.md",
"notes/linux/index.md", "notes/linux/index.md",
"Pasted image 20250422121610.png",
"Pasted image 20250422122034.png", "Pasted image 20250422122034.png",
"notes/index/index.md", "notes/index/index.md",
"Pasted image 20250422123058.png", "Pasted image 20250422123058.png",
"Pasted image 20250422122140.png", "Pasted image 20250422122140.png",
"drafts/bash.md",
"notes/c-language.md", "notes/c-language.md",
"drafts/gobject.md", "drafts/gobject.md",
"drafts/lua.md", "drafts/lua.md",
@@ -235,7 +236,6 @@
"notes/gdb.md", "notes/gdb.md",
"notes/flask.md", "notes/flask.md",
"notes/encryption.md", "notes/encryption.md",
"notes/firewall.md",
"notes/compiling.md", "notes/compiling.md",
"notes/c-snippets.md", "notes/c-snippets.md",
"search.md", "search.md",

2
content/notes/firewall.md
View File

@@ -9,7 +9,7 @@ tags:
author: TrudeEH author: TrudeEH
showToc: true showToc: true
--- ---
A firewall monitors and controls all incoming and outgoing network traffic, and can be implemented in the hardware or software level. A firewall monitors and controls all incoming and outgoing network traffic, and can be implemented at the hardware or software level.
## See All Open Ports ## See All Open Ports

30
content/notes/linux/index.md
View File

@@ -206,11 +206,11 @@ The GPU still has a device file, which is used by the Kernel's DRM and Mesa, but
## Shell (`bash`) ## Shell (`bash`)
The kernel by itself isn't intractable, so a shell is needed for the user to be able to execute programs and run commands. Bash is not only a prompt, but also an interpreter for its own programming language, which can be used to write scripts and automate tasks. The kernel by itself isn't intractable, so a shell is needed for the user to be able to execute programs and run commands. `bash` is not only a prompt, but also an interpreter for its own programming language, which can be used to write scripts and automate tasks.
### Commands ### Commands
Bash performs actions through commands. A shell command consists of the command itself, followed by its arguments. `bash` performs actions through commands. A shell command consists of the command itself, followed by its arguments.
```bash ```bash
command "arg1" "arg2" command "arg1" "arg2"
@@ -218,14 +218,18 @@ command "arg1" "arg2"
If the first word of a command is a reserved word, bash handles the command, otherwise, it searches for an executable on the system's `$PATH`, a list of directories where a binary could be located. If the first word of a command is a reserved word, bash handles the command, otherwise, it searches for an executable on the system's `$PATH`, a list of directories where a binary could be located.
### Bash Scripts ### Shell Scripts
While `bash` is typically used as the login shell, it is slow for script execution. For this reason, many distributions (such as Debian) use `dash` to run `sh` scripts (symlink `/bin/sh` to `/bin/dash`), which is a faster alternative to `bash`, designed specifically to execute scripts and to be strictly POSIX compliant.
When writing scripts, it's a good practice to follow the POSIX standard, to make them compatible with most shells, older systems, and different distributions, while taking advantage of `dash`'s faster performance. Keep in mind that `dash` is not `bash` compatible, and some `bash` commands might not work on `dash`.
Example `script.sh`: Example `script.sh`:
```bash ```bash
#! /bin/bash #! /bin/sh
echo "Bash Script" echo "Shell Script"
``` ```
Execute the script: Execute the script:
@@ -235,15 +239,15 @@ chmod u+x script.sh # Give the script execution permission (to its owner)
./script.sh # Run the script ./script.sh # Run the script
``` ```
After writing a script, use `shellcheck` to check for issues.
### Learning ### Learning
There are some commands available to search for documentation:
```bash ```bash
tldr command # Examples of how to use the command (external tool) tldr command # Examples of how to use the command (external tool)
help command # Short documentation for the command help command # Short documentation for the command
man command # Full documentation for the command man command # Full documentation for the command
man bash # Bash documentation; Includes most built-in commands man dash # Dash documentation; Includes most built-in commands
``` ```
> To get started, use `help` by itself, which provides a list of the built-in commands available in bash. > To get started, use `help` by itself, which provides a list of the built-in commands available in bash.
@@ -253,6 +257,8 @@ For example, suppose you want to learn how to write an `if` statement in `bash`:
![Pasted image 20250422123058](../../Pasted%20image%2020250422123058.png) ![Pasted image 20250422123058](../../Pasted%20image%2020250422123058.png)
As suggested by `tldr`, to see all possible conditions, use the `man test` command. As suggested by `tldr`, to see all possible conditions, use the `man test` command.
> If you are writing scripts using `dash`, it's recommended to read the `dash` manual instead: `man dash`. The `if [[ ]]` syntax is exclusive to `bash`, for example, and should be replaced with `if [ ]` to use with `dash`.
### Compiling ### Compiling
Dependencies: Dependencies:
@@ -286,6 +292,8 @@ sudo apt install ../bash*.deb
Bash includes a set of *builtins*: Command-line utilities that come within bash itself. However, these are very limited, and to actually make the computer useful, more programs are needed. Bash includes a set of *builtins*: Command-line utilities that come within bash itself. However, these are very limited, and to actually make the computer useful, more programs are needed.
> To learn more about a program, use: `man program_name`.
### Coreutils ### Coreutils
*Coreutils* are a collection of small command-line utilities, which are essential for text, file and shell manipulation. *Coreutils* are a collection of small command-line utilities, which are essential for text, file and shell manipulation.