6f682c8405
This is a large change to how io_buffers are filled. The essential problem
comes about with code like (example):
echo ( /bin/pwd )
The output of /bin/pwd must go to fish, not the tty. To arrange for this,
fish does the following:
1. Invoke pipe() to create a pipe.
2. Add an io_bufferfill_t redirection that owns the write end of the pipe.
3. After fork (or equiv), call dup2() to replace pwd's stdout with this pipe.
Now when /bin/pwd writes, it will send output to the read end of the pipe.
But who reads it?
Prior to this fix, fish would do the following in a loop:
1. select() on the pipe with a 10 msec timeout
2. waitpid(WNOHANG) on the pwd proc
This polling is ugly and confusing and is what is replaced here.
With this new change, fish now reads from the pipe via a background thread:
1. Spawn a background pthread, which select()s on the pipe's read end with
a long (100 msec) timeout.
2. In the foreground, waitpid() (allowing hanging) on the pwd proc.
The big win here is a major simplification of job_t::continue_job() since
it no longer has to worry about filling buffers. This will make things
easier for concurrent execution.
It may not be obvious why the background thread still needs a poll (100 msec).
The answer is for cases where the write end of the fd escapes, in particular
background processes invoked inside command substitutions. psub is perhaps
the only important case of this (other shells typically just hang here).
|
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|---|---|---|
| .github | ||
| build_tools | ||
| cmake | ||
| debian | ||
| doc_src | ||
| etc | ||
| fish.xcodeproj | ||
| m4 | ||
| osx | ||
| pcre2-10.32 | ||
| po | ||
| share | ||
| src | ||
| tests | ||
| .clang-format | ||
| .cppcheck.rules | ||
| .cppcheck.suppressions | ||
| .editorconfig | ||
| .gitattributes | ||
| .gitignore | ||
| .oclint | ||
| .travis.yml | ||
| BSDmakefile | ||
| CHANGELOG.md | ||
| CMakeLists.txt | ||
| config.guess | ||
| config.sub | ||
| config_cmake.h.in | ||
| configure.ac | ||
| CONTRIBUTING.md | ||
| COPYING | ||
| Dockerfile | ||
| Doxyfile | ||
| Doxyfile.help | ||
| Doxyfile.user | ||
| fish.pc.in | ||
| fish.spec.in | ||
| install-sh | ||
| lexicon_filter.in | ||
| Makefile.in | ||
| README.md | ||
fish - the friendly interactive shell 
fish is a smart and user-friendly command line shell for macOS, Linux, and the rest of the family. fish includes features like syntax highlighting, autosuggest-as-you-type, and fancy tab completions that just work, with no configuration required.
For more on fish's design philosophy, see the design document.
Quick Start
fish generally works like other shells, like bash or zsh. A few important differences can be found at https://fishshell.com/docs/current/tutorial.html by searching for the magic phrase "unlike other shells".
Detailed user documentation is available by running help within fish, and also at https://fishshell.com/docs/current/index.html
You can quickly play with fish right in your browser by clicking the button below:
Getting fish
macOS
fish can be installed:
- using Homebrew:
brew install fish - using MacPorts:
sudo port install fish - using the installer from fishshell.com
- as a standalone app from fishshell.com
Packages for Linux
Packages for Debian, Fedora, openSUSE, and Red Hat Enterprise Linux/CentOS are available from the openSUSE Build Service.
Packages for Ubuntu are available from the fish PPA, and can be installed using the following commands:
sudo apt-add-repository ppa:fish-shell/release-3
sudo apt-get update
sudo apt-get install fish
Instructions for other distributions may be found at fishshell.com.
Windows
- On Windows 10, fish can be installed under the WSL Windows Subsystem for Linux with
sudo apt install fishor from source with the instructions below. - Fish can also be installed on all versions of Windows using Cygwin (from the Shells category).
Building from source
If packages are not available for your platform, GPG-signed tarballs are available from fishshell.com and fish-shell on GitHub. See the Building section for instructions.
Running fish
Once installed, run fish from your current shell to try fish out!
Dependencies
Running fish requires:
- curses or ncurses (preinstalled on most *nix systems)
- some common *nix system utilities (currently
mktempandseq), in addition to the basic POSIX utilities - gettext (library and
gettextcommand), if compiled with translation support
The following optional features also have specific requirements:
- builtin commands that have the
--helpoption or print usage messages requireuland eithernrofformandocfor display - automated completion generation from manual pages requires Python (2.7+ or 3.3+) and possibly the
backports.lzmamodule for Python 2.7 - the
fish_configweb configuration tool requires Python (2.7+ or 3.3 +) and a web browser - system clipboard integration (with the default Ctrl-V and Ctrl-X bindings) require either the
xselorpbcopy/pbpasteutilities - full completions for
yarnandbowerrequire thejqutility - full completions for
yarnandnpmrequire theall-the-package-namesNPM module
Switching to fish
If you wish to use fish as your default shell, use the following command:
chsh -s /usr/local/bin/fish
chsh will prompt you for your password and change your default shell. (Substitute /usr/local/bin/fish with whatever path fish was installed to, if it differs.)
Use the following command if fish isn't already added to /etc/shells to permit fish to be your login shell:
echo /usr/local/bin/fish | sudo tee -a /etc/shells
To switch your default shell back, you can run chsh -s /bin/bash (substituting /bin/bash with /bin/tcsh or /bin/zsh as appropriate).
Building
Dependencies
Compiling fish requires:
- a C++11 compiler (g++ 4.8 or later, or clang 3.3 or later)
- any of CMake, GNU Make, or (on macOS only) Xcode
- a curses implementation such as ncurses (headers and libraries)
- PCRE2 (headers and libraries) - a copy is included with fish
- gettext (headers and libraries) - optional, for translation support
Additionally, if compiling fish with GNU Make from git (that is, not from an officially released tarball), autoconf 2.60+ and automake 1.13+ are required. Doxygen (1.8.7 or later) is also optionally required to build the documentation from a cloned git repository.
Building from source (all platforms)
Using CMake (preferred)
mkdir build; cd build
cmake ..
make
sudo make install
Using autotools
autoreconf --no-recursive #if building from Git
./configure
make
sudo make install
Building from source (macOS only)
- Build the
basetarget in Xcode - Run the fish executable, for example, in
DerivedData/fish/Build/Products/Debug/base/bin/fish
To build and install fish with Xcode on macOS, execute the following in a terminal:
xcodebuild install
sudo ditto /tmp/fish.dst /
sudo make install-doc
Help, it didn't build!
If fish reports that it could not find curses, try installing a curses development package and build again.
On Debian or Ubuntu you want:
sudo apt-get install build-essential ncurses-dev libncurses5-dev gettext autoconf
On RedHat, CentOS, or Amazon EC2:
sudo yum install ncurses-devel
Contributing Changes to the Code
See the Guide for Developers.
Contact Us
Questions, comments, rants and raves can be posted to the official fish mailing list at https://lists.sourceforge.net/lists/listinfo/fish-users or join us on our gitter.im channel or IRC channel #fish at irc.oftc.net. Or use the fish tag on Stackoverflow for questions related to fish script and the fish tag on Superuser for all other questions (e.g., customizing colors, changing key bindings).
Found a bug? Have an awesome idea? Please open an issue.