More work on intro to command line

mattpopovich · May 21, 2024 · 988af99 · 988af99
1 parent 287accf
commit 988af99
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diff --git a/_posts/2024-05-15-introduction-to-the-command-line--shell--terminal-etc.md b/_posts/2024-05-15-introduction-to-the-command-line--shell--terminal-etc.md
@@ -21,14 +21,14 @@ mermaid: false              # Diagram generation tool via ```mermaid [...]```
 #description:               # A short sentence to describe the article, used when sharing links on social media
 ---
 
-## Intro to the Terminal
+# Intro to the Terminal
 
-### Disclaimer
+## Disclaimer
 *Command line*, *command prompt*, *shell*, *terminal*, *console*, etc. can sometimes be used interchangeably. Normally, they are all referring to a window in which you input text commands and receive text output.
 
 There are **a lot** of intricacies in the terminal. You might call them ["quirks"](https://youtu.be/2aiopbNnyF8) or ["features"](https://youtu.be/BQ0mlXQezxE?si=ijwZunxB5kDFciGI). You will never learn them all and some of them still stump me to this day. However, most of the terminal follows the same general pattern:
 
-### How to Use
+## How to Use
 The terminal is made up of three possible things:
 ```console
 $ program -flags arguments
@@ -44,7 +44,8 @@ A `$` or `#` are common hints that this line is meant to be ran in a terminal
 * `arguments` are information given to a program for it to act upon (just like function arguments)
   * *Optional*
 
-### Example
+## Example Use
+### `ls`
 `ls` = *a program used to list files*
 ```console
 $ ls
@@ -70,6 +71,9 @@ drwx------+   7 mattpopovich  staff          224 Apr 13 10:14 Pictures
 
 `ls` supports multiple flags. We can also include `-h` = *list files in a more **h**uman readable format*
 
+> Note that this gives you the size of the file. This does not give you the size of the files in the folder!! (Use `du` for that)
+{:.prompt-warn}
+
 ```console
 $ ls -lh
 total 8
@@ -110,6 +114,8 @@ Very handy whenever you are in a folder with lots of files!
 ### Other programs
 Here, I will be using the term *program* but note that there are again many terms that are sometimes used interchangeably: *program*, *executable*, *script*, *binary*, *command*, etc.
 
+### `cd`
+
 `cd` = ***c**hange **d**irectory*
 
 Your terminal will normally show what directory you are currently in before each command. This helps keep you oriented to what folder you are currently operating in!
@@ -157,29 +163,181 @@ Downloads
 01_Not_Like_Us-Kendrick_Lamar.mp3
 ```
 
+Notice that `/users/mattpopovich` is being displayed as `~`.
+
+### `man`
+
+`man` = *Display **man**ual documentation pages*
+
+This command displays documentation for the argument you pass to it.
+
+```console
+$ man ls
+LS(1)                                      General Commands Manual                                      LS(1)
+
+NAME
+     ls – list directory contents
+
+SYNOPSIS
+     ls [-@ABCFGHILOPRSTUWabcdefghiklmnopqrstuvwxy1%,] [--color=when] [-D format] [file ...]
+
+DESCRIPTION
+     For each operand that names a file of a type other than directory, ls displays its name as well as any
+     requested, associated information.  For each operand that names a file of type directory, ls displays
+     the names of files contained within that directory, as well as any requested, associated information.
+
+     If no operands are given, the contents of the current directory are displayed.  If more than one operand
+     is given, non-directory operands are displayed first; directory and non-directory operands are sorted
+     separately and in lexicographical order.
+
+     The following options are available:
+
+     -@      Display extended attribute keys and sizes in long (-l) output.
+
+     -A      Include directory entries whose names begin with a dot (‘.’) except for . and ...  Automatically
+             set for the super-user unless -I is specified.
+
+     -B      Force printing of non-printable characters (as defined by ctype(3) and current locale settings)
+             in file names as \xxx, where xxx is the numeric value of the character in octal.  This option is
+             not defined in IEEE Std 1003.1-2008 (“POSIX.1”).
+[...]
+```
+
+Note that once you run `man`, a new "window" in the terminal opens. You can navigate it with the enter key, up and down errors, or even scrolling (if enabled). Press `q` (quit) to exit. `q` to exit is common in other programs as well (`vi`) as we will find out.
+
+### `touch`
+
+`touch` = change file access and modification times
+
+Personally, I never use this command for its intended purpose. I only use it for creating new, empty files.
+
+```console
+$ man touch
+[...]
+The touch utility sets the modification and access times of files.  If any file does not exist, it is
+     created with default permissions.
+[...]
+$ ls
+$ touch test_file.txt
+$ ls -l
+total 0
+-rw-r--r--  1 mattpopovich  staff  0 Feb 31 20:42 test_file.txt
+```
+
+### `mkdir`
+
+`mkdir` = ***m**a**k**e **dir**ectories*
 
+```console
+$ ls -l
+total 0
+-rw-r--r--  1 mattpopovich  staff  0 Feb 31 20:42 test_file.txt
+$ mkdir test_folder
+$ ls -l
+total 0
+-rw-r--r--  1 mattpopovich  staff   0 Feb 31 20:42 test_file.txt
+drwxr-xr-x  2 mattpopovich  staff  64 Feb 31 20:49 test_folder
+```
 
+### `mv`
+`mv` = ***m**o**v**e files*
 
+Now that we know how to make files and folders, let's learn how to customize things a bit.
 
+```console
+$ ls
+test_file.txt test_file2.txt test_file3.txt test_folder
+$ ls test_folder
+$ mv test_file.txt test_folder
+$ ls
+test_file2.txt test_file3.txt test_folder
+$ ls test_folder
+test_file.txt
+$ mv test_file* test_folder
+$ ls
+test_folder
+$ ls test_folder
+test_file.txt test_file2.txt test_file3.txt
+```
 
+The `mv` command can also be used to effectively rename files and folders (by moving them to a new name)
 
+```console
+$ ls
+test_folder
+$ ls test_folder
+test_file.txt
+$ mv test_folder testing_folder
+$ ls
+testing_folder
+$ ls testing_folder
+test_file.txt
+```
 
-* cd = change directory
-* ls = list files
-  * ll
-  * Glob patterns
-  * ..
-* mv = move files
-* cp = copy
-* rm = remove
-* man = manual
-* help = help
-* vi / vim
+### `cp`
+`cp` = ***c**o**p**y files*
+
+This is used the same as the `mv` command above, but it copies the files instead of moving them.
+
+```console
+$ ls
+test_file.txt test_file2.txt test_file3.txt test_folder
+$ ls test_folder
+$ cp test_file.txt test_folder
+$ ls
+test_file.txt test_file2.txt test_file3.txt test_folder
+$ ls test_folder
+test_file.txt
+$ cp test_file* test_folder
+$ ls
+test_file.txt test_file2.txt test_file3.txt test_folder
+$ ls test_folder
+test_file.txt test_file2.txt test_file3.txt
+```
+
+### `rm`
+`rm` = ***r**e**m**ove*
+* `-d` = remove **d**irectory
+* `-R` = **r**ecursively remove things in a directory. Implies the **-d** option
+* `-r` = Equivalent to `-R`
+
+This command will remove files and folders
+
+```console
+$ ls
+test_file.txt test_folder
+$ ls test_folder
+$ rm test_file.txt
+test_folder
+$ rm test_folder
+rm: test_folder: is a directory
+$ rm -d test_folder
+```
+
+```
+$ ls
+file1 test_folder
+$ ls test_folder
+file2
+$ ls *
+file1
+
+test_folder:
+file2
+$ rm -d test_folder
+rm: test_folder: Directory not empty
+$ rm -r test_folder
+$ ls
+file1
+```
+
+### Other helpful commands
+
+* --help = help
 * grep
 * cat
 * head
 * tail
-* touch
 * | = pipe
 * find
 * exit
@@ -192,7 +350,6 @@ Downloads
 * pwd = present working directory
 * which
 * !!
-* mkdir
 * source
 * chmod
 * chown
@@ -204,16 +361,57 @@ Downloads
 * curl
 * rsync
 * Multiple commands; on one line
+* bg, fg
+* ctrl+c, ctrl+\, ctrl+z
 
 
+## Return values
+Notice that with all the commands we've ran, when they are successful, they largely don't display anything (unless when that is their job, such as `ls`). This is by design. No output is typically indicative of success, output is typically signs that something went wrong.
+
+```console
+$ ls
+test_file.txt test_folder
+$ rm test_file.txt
+$ rm test_file.txt
+rm: test_file.txt: No such file or directory
+$ rm test_folder
+rm: test_folder: is a directory
+$ ls
+test_folder
+```
+
+## Interactive Commands
+
+There are multiple "editors" available to use in the command prompt. Engineers will have their own (sometimes strong) preference as to which one you should use. I just use `vi` and for no particular reason other than I know how to use it and I don't use it enough to warrant learning other editors.
+
+### `vi` / `vim`
+
+`vi` = ***vi**sual*
+`vim` = ***vi** i**m**proved*
+
+```console
+$ ls
+$ vi text_file.txt
+```
+
+From here, we are kicked into the editor. It can be a little daunting at first but here are some of its commands. These are entered in once `vi` is open. These are not command line arguments.
+* `i` = go into "insert" mode
+
+Additional commands can be found [here](https://www.cs.colostate.edu/helpdocs/vi.html).
+
 
-Arguments
 
 Environment variables
 
-.bash_rcHidden filesDifferent shells
+.bash_rc
+
+Hidden files
+
+Different shells
 
 Programs are in your path
 
 Tab complete
 
+ctrl+w, ctrl+u, ctrl+left, ctrl+right
+