Linux — Learning Library

The prompt

Linux — Learning Library

Linux — a learning library
Start Here
Start Here
Pipelines
Pipelines
- A pipeline reports its last command
  A pipeline reports its last command
- stderr does not go down the pipe
  stderr does not go down the pipe
- Each stage runs in a subshell
  Each stage runs in a subshell
- A program knows it is piped
  A program knows it is piped
- head closes the pipe early
  head closes the pipe early
Redirection
Redirection
- Descriptors 0, 1 and 2
  Descriptors 0, 1 and 2
- stdout and stderr go separately
  stdout and stderr go separately
- Redirection truncates first
  Redirection truncates first
- Input from a file, a string, a here-document
  Input from a file, a string, a here-document
tee
tee
- tee saves and passes on
  tee saves and passes on
- sudo tee writes where redirection cannot
  sudo tee writes where redirection cannot
- tee into several commands
  tee into several commands
- tee and the exit status
  tee and the exit status
grep
grep
- ls | grep alma | wc -l counts lines, not files
  ls | grep alma | wc -l counts lines, not files
- cat file | grep is one process too many
  cat file | grep is one process too many
- The everyday options: -i -v -w -n -o -c -l -h -r
  The everyday options: -i -v -w -n -o -c -l -h -r
- grep exits 0, 1 or 2
  grep exits 0, 1 or 2
- GNU grep and BSD grep: what travels and what does not
  GNU grep and BSD grep: what travels and what does not
tr
tr
- A tr class is a set, and only two of them translate
  A tr class is a set, and only two of them translate
- An unquoted [:lower:] is a glob
  An unquoted [:lower:] is a glob
History
History
- The history is a list in memory
  The history is a list in memory
- Two terminals, one history file
  Two terminals, one history file
- What gets remembered
  What gets remembered
- History expansion
  History expansion
- Three history file formats
  Three history file formats
fzf
fzf
- fzf is a filter
  fzf is a filter
- Fuzzy means in order
  Fuzzy means in order
- The extended search syntax
  The extended search syntax
- Smart case, and cafe finding Café
  Smart case, and cafe finding Café
- Ctrl-R is a pipeline
  Ctrl-R is a pipeline
Prompt
Prompt
- PS1 belongs to bash
  PS1 belongs to bash
- Which startup file runs
  Which startup file runs
Files
Files
- The first letter of ls -l is the type
  The first letter of ls -l is the type
- What a dot means to the shell
  What a dot means to the shell
Resources
Resources

The prompt¶

One line: The prompt is drawn by the shell, not the terminal, and each shell has its own language for it: PS1 with backslash escapes in bash, PROMPT with percent escapes in zsh, and in fish a function called fish_prompt.

Lesson	Level	What it settles
`PS1` belongs to bash	101	The book's `[\u@\h \W]\$` and `[\d \t \u@\h \w]\$` drawn by bash, zsh and fish; `%` escapes, `fish_prompt` and `funcsave`; `${PS1@P}` and the login shell on a Mac
Which startup file runs	101	`~/.bashrc`, `~/.bash_profile`, `~/.profile`, `~/.zshenv`, `~/.zprofile`, `~/.zshrc` and `config.fish` for login and interactive shells, and the `/etc` files that run before them