Skip to content
Linux shell for iOS
C Objective-C Assembly C++ Shell Meson Other
Branch: master
Clone or download


Type Name Latest commit message Commit time
Failed to load latest commit information.
.github Add github sponsors to the FUNDING.yml Apr 25, 2020
app Release build 70 to testflight Jun 2, 2020
emu Fix sqrt(0) returning NaN Jun 1, 2020
fastlane Make an attempt to automate posting release notes to Discord Jun 2, 2020
fs Fix displaying negative numbers in emacs May 31, 2020
iSH.xcodeproj Release build 70 to testflight Jun 2, 2020
jit Change psllq/pslrq/paddq helper function names May 31, 2020
kernel Squash some GCC warnings that only appear when compiling with optimiz… May 31, 2020
platform Return the correct answer for total system memory on Darwin Oct 14, 2019
subprojects Remove gdbm Nov 30, 2018
tests Implement orpd, punpcklqdq, pminub, pand, por, paddb May 31, 2020
tools Squash some GCC warnings that only appear when compiling with optimiz… May 31, 2020
util Fix warning on zeroing out lock->owner May 30, 2020
vdso Remove fill directive from linker script Sep 30, 2019
.editorconfig apply 4 space to everything, utf-8 May 14, 2019
.gitignore add end to end testing script, two example tests, and travis Jun 7, 2019
.gitmodules Fix submodule path Sep 7, 2019
.travis.yml Enable gcc on travis (#745) May 31, 2020 Update changelog Feb 12, 2019 Update Mar 31, 2019
LICENSE Use GPL, not LGPL Oct 11, 2018
LICENSE.IOS Add license terms to allow App Store distribution Nov 10, 2018 Update Discord link May 28, 2020 Update Discord link in May 28, 2020
debug.h Don't warn about variables only used in log statements Feb 10, 2020
iSH.xcconfig Get app group IDs from entitlements Mar 1, 2020
ish-gdb.gdb Ignore SIGPIPE in gdb Sep 30, 2018
main.c Make iosfs unsafe into a mount option Apr 13, 2020 Add meson option for declaring SSE2 support. (#746) May 31, 2020
meson_options.txt Add meson option for declaring SSE2 support. (#746) May 31, 2020
misc.h Squash some GCC warnings that only appear when compiling with optimiz… May 31, 2020
xX_main_Xx.h Squash a ton of warnings, including with gcc May 31, 2020 Deal with breaking change in Meson 0.54.0 Apr 11, 2020


Build Status goto counter fuck counter

A project to get a Linux shell running on iOS, using usermode x86 emulation and syscall translation.

For the current status of the project, check the issues tab, and the commit logs.


This project has a git submodule, make sure to clone with --recurse-submodules or run git submodule update --init after cloning.

You'll need these things to build the project:

  • Python 3
  • Ninja
  • Meson (pip install meson)
  • Clang and LLD (on mac, brew install llvm, on linux, sudo apt install clang lld or sudo pacman -S clang lld or whatever)
  • sqlite3 (this is so common it may already be installed on linux and is definitely already installed on mac. if not, do something like sudo apt install libsqlite3-dev)

Build for iOS

Open the project in Xcode, open iSH.xcconfig, and change ROOT_BUNDLE_IDENTIFIER to something unique. Then click Run. There are scripts that should do everything else automatically. If you run into any problems, open an issue and I'll try to help.

Build command line tool for testing

To set up your environment, cd to the project and run meson build to create a build directory in build. Then cd to the build directory and run ninja.

To set up a self-contained Alpine linux filesystem, download the Alpine minirootfs tarball for i386 from the Alpine website and run the tools/ script. Specify the minirootfs tarball as the first argument and the name of the output directory as the second argument. Then you can run things inside the Alpine filesystem with ./ish -f alpine /bin/login -f root, assuming the output directory is called alpine.

You can replace ish with tools/ptraceomatic to run the program in a real process and single step and compare the registers at each step. I use it for debugging. Requires 64-bit Linux 4.11 or later.


iSH has several logging channels which can be enabled at build time. By default, all of them are disabled. To enable them:

  • In Xcode: Set the ISH_LOG setting in iSH.xcconfig to a space-separated list of log channels.
  • With Meson (command line tool for testing): Run meson configure -Dlog="<space-separated list of log channels>.

Available channels:

  • strace: The most useful channel, logs the parameters and return value of almost every system call.
  • instr: Logs every instruction executed by the emulator. This slows things down a lot.
  • verbose: Debug logs that don't fit into another category.
  • Grep for DEFAULT_CHANNEL to see if more log channels have been added since this list was updated.

A note on the JIT

Possibly the most interesting thing I wrote as part of iSH is the JIT. It's not actually a JIT since it doesn't target machine code. Instead it generates an array of pointers to functions called gadgets, and each gadget ends with a tailcall to the next function; like the threaded code technique used by some Forth interpreters. The result is a speedup of roughly 3-5x compared to pure emulation.

Unfortunately, I made the decision to write nearly all of the gadgets in assembly language. This was probably a good decision with regards to performance (though I'll never know for sure), but a horrible decision with regards to readability, maintainability, and my sanity. The amount of bullshit I've had to put up with from the compiler/assembler/linker is insane. It's like there's a demon in there that makes sure my code is sufficiently deformed, and if not, makes up stupid reasons why it shouldn't compile. In order to stay sane while writing this code, I've had to ignore best practices in code structure and naming. You'll find macros and variables with such descriptive names as ss and s and a. Assembler macros nested beyond belief. And to top it off, there are almost no comments.

So a warning: Long-term exposure to this code may cause loss of sanity, nightmares about GAS macros and linker errors, or any number of other debilitating side effects. This code is known to the State of California to cause cancer, birth defects, and reproductive harm.

You can’t perform that action at this time.