114 lines
3.6 KiB
Org Mode
114 lines
3.6 KiB
Org Mode
#+title: lesson 02 | course overview + the shell
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../_share/media/css/missing-semester.css" />
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#+HTML_HEAD: <link rel="stylesheet" type="text/css" href="../_share/media/css/org-media-sass/collapsible.css" />
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#+HTML_HEAD: <script src="../_share/media/js/collapsible.js"></script>
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* Links
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#+attr_html: :class links
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- [[../toc.org][TOC | Missing Semester]]
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- [[https://www.youtube.com/playlist?list=PLyzOVJj3bHQuloKGG59rS43e29ro7I57J][Playlist: Missing Semester]]
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*** timestamps
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:PROPERTIES:
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:CUSTOM_ID: timestamp
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:END:
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#+attr_html: :class playlist
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=54s][00:54 - control flow functions]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=227s][03:47 - sequential execution]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=425s][07:05 - standard input]] *current*
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=444s][07:24 - error code]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=517s][08:37 - logical operators]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=603s][10:03 - concatenate commands]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=645s][10:45 - common substitution]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=675s][11:15 - process substitution]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=935s][15:35 - comparison operator]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=1173s][19:33 - curly braces]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=1359s][22:39 - python script]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=1707s][28:27 - man command]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=2175s][36:15 - finding files]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=2190s][36:30 - grep]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=2573s][42:53 - fuzzy finder]]
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+ [[https://www.youtube.com/watch?v=kgII-YWo3Zw&t=2649s][44:09 - history substring search]]
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* Notes
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** bash
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*** spaces are critical with bash
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- this works:
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#+begin_src bash
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foo=bar
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echo $foo
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#+end_src
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- this doesn't:
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#+begin_src bash
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foo = bar
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echo $foo
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#+end_src
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- the output of that will be
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=zsh: command not found: foo=
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- what happens in the above example is that we are effectively calling the "foo" program with the arguments: "=" and "bar"
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*** quotes
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- you can use double or single quotes to print a value
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#+begin_src bash
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echo "Hello"
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#+end_src
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#+begin_src bash
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echo 'Hello'
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#+end_src
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- double quotes can interpolate variables
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#+begin_src bash
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echo "Value is $foo"
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#+end_src
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will return: =Value is bar=
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- single quotes can NOT interpoloate variables
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#+begin_src bash
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echo 'Value is $foo'
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#+end_src
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will return: =Value is $foo=
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** sequential execution
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*** bash functions
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- mcd.sh
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#+begin_src bash
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mcd() {
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mkdir -p "$1"
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cd "$1"
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}
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#+end_src bash
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- creates a function that can be executed after loading
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- $1 is a global variable referring to the first parameter
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*** source
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- using source mcd.sh
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=source mcd.sh=
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- then carry out the function
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=mcd testdir=
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- this will create a new directory and cd into it as per the definied functioned
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*** variables
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- $0 -- name of the script we are currently in
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- if you run this in the shell it will display 'bash'
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- $1->$9 -- the first through ninth argument given to a script
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- $? -- the last error message
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- $_ --- last argument of the previous call
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- !! -- recreates the last call with it's arguments
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- use with sudo if you found your call needed a sudo and you don't feel like retyping it again
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#+begin_src bash
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ls -lah
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sudo !!
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#+end_src
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