110 lines
2.9 KiB
Markdown
110 lines
2.9 KiB
Markdown
|
# Origin
|
||
|
|
|
||
|
|
- Used as a 'shell' around a bare-ass kernel.
|
||
|
|
- People once considered a basic shell user-friendly.
|
||
|
|
|
||
|
|
## Use Cases
|
||
|
|
|
||
|
|
- It's crazy-fast
|
||
|
|
- Try deleting a file in Python.
|
||
|
|
|
||
|
|
## Form
|
||
|
|
|
||
|
|
- Big mess of binaries, wrapped together
|
||
|
|
- Janky mess
|
||
|
|
|
||
|
|
# Bangs!
|
||
|
|
|
||
|
|
Don't say `#!/bin/bash` if you don't mean it!
|
||
|
|
|
||
|
|
| Bang! | Apraisal |
|
||
|
|
|:---------------|:--------------|
|
||
|
|
| `#!/bin/bash` | reasonable |
|
||
|
|
| `#!/bin/sh` | sensible |
|
||
|
|
| `#!/bin/dash` | bad idea |
|
||
|
|
| `#!/bin/zsh` | risky |
|
||
|
|
| `#!/bin/ksh` | foolish |
|
||
|
|
| `#!/bin/fish` | madness |
|
||
|
|
| `#!/bin/elvish`| genius |
|
||
|
|
|
||
|
|
Protip: for a faster machine, make `sh` a link to `/bin/dash`.
|
||
|
|
|
||
|
|
`ln -s /bin/dash /bin/dash`
|
||
|
|
|
||
|
|
# Deviant Shells
|
||
|
|
|
||
|
|
## `ksh` (korn shell)
|
||
|
|
|
||
|
|
- Can be posix compliant with effort.
|
||
|
|
- vi mode by default.
|
||
|
|
|
||
|
|
## `elvish`
|
||
|
|
|
||
|
|
- pure style
|
||
|
|
- built-in browser
|
||
|
|
- Ctrl+i to search for commands in $PATH
|
||
|
|
- Ctrl+n to search for command arguments
|
||
|
|
- Ctrl+l to return to previous locations
|
||
|
|
|
||
|
|
## Bash Advantages
|
||
|
|
|
||
|
|
- Equality check with "==".
|
||
|
|
* Dash cannot do `if [ $x == 3 ]; then echo y; fi`
|
||
|
|
- `$RANDOM`
|
||
|
|
- Dash cannot use `&>/dev/null`
|
||
|
|
- No history
|
||
|
|
|
||
|
|
# Protips
|
||
|
|
|
||
|
|
```
|
||
|
|
"\C- ": shell-expand-line
|
||
|
|
"\C-x": glob-expand-word
|
||
|
|
```
|
||
|
|
|
||
|
|
- `set -o vi`
|
||
|
|
- Ctrl+d
|
||
|
|
- `type $whatevre`
|
||
|
|
- `.inputrc`
|
||
|
|
|
||
|
|
# Fun with Bash
|
||
|
|
|
||
|
|
- wifi_qr.sh
|
||
|
|
- clean.sh
|
||
|
|
- theme.sh
|
||
|
|
|
||
|
|
# Zen Master Foo
|
||
|
|
|
||
|
|
Master Foo once said to a visiting programmer: "There is more Unix-nature in one line of shell script than there is in ten thousand lines of C."
|
||
|
|
|
||
|
|
The programmer, who was very proud of his mastery of C, said: "How can this be?
|
||
|
|
C is the language in which the very kernel of Unix is implemented!"
|
||
|
|
|
||
|
|
Master Foo replied: "That is so.
|
||
|
|
Nevertheless, there is more Unix-nature in one line of shell script than there is in ten thousand lines of C."
|
||
|
|
|
||
|
|
#
|
||
|
|
|
||
|
|
The programmer grew distressed. "But through the C language we experience the enlightenment of the Patriarch Ritchie! We become as one with the operating system and the machine, reaping matchless performance!"
|
||
|
|
|
||
|
|
Master Foo replied: "All that you say is true.
|
||
|
|
But there is still more Unix-nature in one line of shell script than there is in ten thousand lines of C."
|
||
|
|
|
||
|
|
The programmer scoffed at Master Foo and rose to depart.
|
||
|
|
But Master Foo nodded to his student Nubi, who wrote a line of shell script on a nearby whiteboard, and said: "Master programmer, consider this pipeline.
|
||
|
|
Implemented in pure C, would it not span ten thousand lines?"
|
||
|
|
|
||
|
|
#
|
||
|
|
|
||
|
|
The programmer muttered through his beard, contemplating what Nubi had written.
|
||
|
|
Finally he agreed that it was so.
|
||
|
|
|
||
|
|
"And how many hours would you require to implement and debug that C program?" asked Nubi.
|
||
|
|
|
||
|
|
"Many," admitted the visiting programmer. "But only a fool would spend the time to do that when so many more worthy tasks await him."
|
||
|
|
|
||
|
|
"And who better understands the Unix-nature?" Master Foo asked. "Is it he who writes the ten thousand lines, or he who,
|
||
|
|
perceiving the emptiness of the task, gains merit by not coding?"
|
||
|
|
|
||
|
|
Upon hearing this, the programmer was enlightened.
|
||
|
|
|