Shell Note

Content of this should be considered always under zsh, unless otherwise specified.

@2021-11-25
manual Bash Guide for Beginners also in programming-docs
How to check if a command succeeded?
: is the placeholder like python pass Bash syntax error when "else" follows an empty "then" clause
[ ] if syntax: why if <exp> and if [flag-exp]?
[ ] if syntax: why is the last space in if [[ ]] ; needed?
There's a thing called Parameter Expansion like vscode textmate used
Use string variable as path: the ' and " will effect the string parser, like python f-string. Don't use any delimiter on the definition. Do use quote variable de-references: echo "$games" when quoting from How to add path with space in Bash variable
[ ] what is $() and (). $(cd <path> && pwd) won't work but without $ it works. derived from:Temporarily change current working directory in bash to run a command
open chrome with terminal /usr/bin/open -a "/Applications/Google Chrome.app" 'http://google.com/' from How can I open a URL in Google Chrome from the terminal in OS X?

@2021-11-26
objective is to delete all folder/files expect those under folder res/ (background: MkDocs needs the resources all under doc_dir)
This is called glob or globbing in tldp and Wiki: glob. Here are some examples
! not working in zsh, use ^ instead: [!] (exclamation mark in brackets) wildcard in bash
man find shows that the regex seems bounded with ^ and $.
Running a executable file in Mac 12.0 will actually use sh, checked with ps -p $$

zsh is not shell. When executing read -q , shell will throw an error while zshell has a builtin flag to read only one key and parse to "y" or "n"

to check builtin functions like which, we can use

shell unalias run-help autoload run-help bindkey "^[h" run-help # input `type «Alt-h»' to run-help on type, but it's

(@2021-11-28) Mac zsh has a special constraint shown as Can't open input file: zsh

In macOS Transparency Consent and Control (TCC) restricts access to "personal" data, including anything in a user's Desktop folder and outputs a /bin/zsh: can't open input file error message if you try to disobey this rule. Try moving file-name.zsh to a different folder.

(@2021-11-28) The exact TCC protected folders are listed here MacOS Catalina launchd can't open input file error

These specific folders are TCC protected in Catalina: ~/Desktop, ~/Documents, ~/Downloads, iCloud Drive, third-party cloud storage, if used, removable volumes, network volumes.

(@2021-12-01) The TCC will not block source some-script.zsh nor these files(also .sh, .bash) to run directly.

@2021-12-01
calling a function requires none () in mac terminal, but in VSCode terminal on Mac, the () is accepted.
failing will be silent by default.
- [ ] how to change this? Test: Use set -o errexit to make it throw error. set -o pipefail to make it throw error if any command in pipe fails. also test setopt ERR_EXIT (setopt ERR_EXIT=true) (suggested by Copilot)

1	`ln -s /path/to/original /path/to/link`

@2022-01-26
mydir=${0:a:h}, ${0} is the file path. More details: Portable way to get script's absolute path?
@2022-01-17
[wrong] The $PWD in zsh is the directory of the current runtime shell ~~file~~.
Bash script absolute path with OS X