Surviving bash

The flagship product of modern unix is certainly better than any other 80s shell

August 10, 2018 — October 18, 2018

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General, not macOS-specific or Linux-specific, and see also shells to yak-shave your way into whole other shell paradigms. Or fish for a less awful user experience.

I just don’t care enough to remember. This makes me a Bad Hacker.

1 Command line tips

See command lines which are mostly bash specific because everything is hard in bash.

2 bash history

History tips:

!n — the nth history, !-n the nth-most-recent !string refers to the most recent command in the history starting with string, !?string[?] refers to the most recent command containing string
Configuring bash history to allow two shells at once wow.
Oh wait, it’s harder than you thought.

2.1 Sensible history search

Whack this in .inputrc

set meta-flag on
set input-meta on
set output-meta on
set convert-meta off

"\ep": history-search-backward
"\en": history-search-backward
"\e[A": history-search-backward
"\e[B": history-search-forward

$if Bash
    Space: magic-space
$endif

3 Vars, expansions, filenames, whitespace hell

3.1 Tilde expansion

Tilde expansion is complicated. Best to avoid tildes and use ${HOME}.

3.2 files extension munging in bash

for file in *.html;
    mv "$file" "`basename $file .html`.txt";
done

or:

mv "$file" "${file%.html}.txt"

Don’t forget the quotes, or it will explode when you have spaces in your filenames and delete stuff that you loved. (bash has hurt me so often; why have I not abandoned it?.)

4 For loops

Watch out for horrible problems with handling of delimiters. Anyway, for loops are not insane.

#!/bin/bash

for i in $( ls ); do
    echo item: $i
done

5 Init file madness

Weird bash syntax errors about ‘end of file’.