README
¶
u-root
Description
u-root contains simple Go versions of many standard Linux tools, similar to busybox. It's a pure Go userland!
u-root stands for "universal root". It can create an initramfs in two different modes:
-
source mode: Go toolchain binaries + simple shell + Go source for tools to be compiled on the fly by the shell.
When you try to run a command that is not built, it is compiled first and stored in tmpfs. From that point on, when you run the command, you get the one in tmpfs. Don't worry: the Go compiler is pretty fast.
-
bb mode: One busybox-like binary comprising all the Go tools you ask to include.
In this mode, u-root copies and rewrites the source of the tools you asked to include to be able to compile everything into one busybox-like binary.
Usage
Make sure your Go version is 1.11. Make sure your GOPATH is set
up correctly.
Download and install u-root:
go get github.com/u-root/u-root
You can now use the u-root command to build an initramfs. Here are some examples:
# Build a bb-mode cpio initramfs of all the Go cmds in ./cmds/...
u-root -build=bb
# Generate a cpio archive named initramfs.cpio.
u-root -format=cpio -build=source -o initramfs.cpio
# Generate a bb-mode archive with only these given commands.
u-root -format=cpio -build=bb ./cmds/{init,ls,ip,dhclient,wget,tcz,cat}
-format=cpio and -build=source are the default flag values. The default set
of packages included is all packages in github.com/u-root/u-root/cmds/....
In addition to using paths to specify Go source packages to include, you may
also use Go package import paths (e.g. golang.org/x/tools/imports) to include
commands. Only the main package and its dependencies in those source
directories will be included. For example:
You can build the initramfs built by u-root into the kernel via the
CONFIG_INITRAMFS_SOURCE config variable or you can load it separately via an
option in for example Grub or the QEMU command line or coreboot config variable.
A good way to test the initramfs generated by u-root is with qemu:
qemu-system-x86_64 -kernel path/to/kernel -initrd /tmp/initramfs.linux_amd64.cpio
Note that you do not have to build a special kernel on your own, it is
sufficient to use an existing one. Usually you can find one in /boot.
NOTE: you can compress the initramfs but for xz compression, the kernel has some restrictions on the compression options and it is suggested to align the file to 512 byte boundaries
shell xz --check=crc32 -9 --lzma2=dict=1MiB --stdout /tmp/initramfs.linux_amd64.cpio \ | dd conv=sync bs=512 of=/tmp/initramfs.linux_amd64.cpio.xz
You may also include additional files in the initramfs using the -files flag.
If you add binaries with -files are listed, their ldd dependencies will be
included as well. As example for Debian, you want to add two kernel modules for
testing, executing your currently booted kernel:
NOTE: these files will be placed in the
$HOMEdir in the initramfs.
u-root -files "$HOME/hello.ko $HOME/hello2.ko"
qemu-system-x86_64 -kernel /boot/vmlinuz-$(uname -r) -initrd /tmp/initramfs.linux_amd64.cpio
To specify the location in the initramfs, use <sourcefile>:<destinationfile>.
For example:
u-root -files "root-fs/usr/bin/runc:usr/bin/run"
Getting Packages of TinyCore
Using the tcz command included in u-root, you can install tinycore linux
packages for things you want.
You can use QEMU NAT to allow you to fetch packages. Let's suppose, for example, you want bash. Once u-root is running, you can do this:
% tcz bash
The tcz command computes and fetches all dependencies. If you can't get to tinycorelinux.net, or you want package fetching to be faster, you can run your own server for tinycore packages.
You can do this to get a local server using the u-root srvfiles command:
% srvfiles -p 80 -d path-to-local-tinycore-packages
Of course you have to fetch all those packages first somehow :-)
Build an Embeddable U-root
You can build this environment into a kernel as an initramfs, and further embed that into firmware as a coreboot payload.
In the kernel and coreboot case, you need to configure ethernet. We have a
dhclient command that works for both ipv4 and ipv6. Since v6 does not yet work
that well for most people, a typical invocation looks like this:
% dhclient -ipv4 -ipv6=false
Or, on newer linux kernels (> 4.x) boot with ip=dhcp in the command line, assuming your kernel is configured to work that way.
Updating Dependencies
# The latest released version of dep is required:
curl https://raw.githubusercontent.com/golang/dep/master/install.sh | sh
dep ensure
Hardware
If you want to see u-root on real hardware, this board is a good start.
Contributions
See CONTRIBUTING.md
Improving existing commands (e.g., additional currently unsupported flags) is
very welcome. In this case it is not even required to build an initramfs, just
enter the cmds/ directory and start coding. A list of commands that are on the
roadmap can be found here.
Documentation
¶
There is no documentation for this package.
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
|
cmds
|
|
|
ansi
Print ansi escape sequences.
|
Print ansi escape sequences. |
|
basename
Basename return name with leading path information removed.
|
Basename return name with leading path information removed. |
|
bzimage
bzImage is used to modify bzImage files.
|
bzImage is used to modify bzImage files. |
|
cat
Cat concatenates files and prints to stdout.
|
Cat concatenates files and prints to stdout. |
|
cbmem
cbmem prints out coreboot mem table information in JSON by default, and also implements the basic cbmem -list and -console commands.
|
cbmem prints out coreboot mem table information in JSON by default, and also implements the basic cbmem -list and -console commands. |
|
chmod
Change modifier bits of a file.
|
Change modifier bits of a file. |
|
cmp
Cmp compares two files and prints a message if their contents differ.
|
Cmp compares two files and prints a message if their contents differ. |
|
comm
Perform a set comparisons over two files.
|
Perform a set comparisons over two files. |
|
console
console implements a basic console.
|
console implements a basic console. |
|
cp
Copy files.
|
Copy files. |
|
cpio
cpio operates on cpio files using a cpio package It only implements basic cpio options.
|
cpio operates on cpio files using a cpio package It only implements basic cpio options. |
|
date
Print the date.
|
Print the date. |
|
dd
Convert and copy a file.
|
Convert and copy a file. |
|
dhclient
dhclient sets up DHCP.
|
dhclient sets up DHCP. |
|
dirname
dirname prints out the directory name of one or more args.
|
dirname prints out the directory name of one or more args. |
|
dmesg
Read the system log.
|
Read the system log. |
|
echo
Echo writes its arguments separated by blanks and terminated by a newline on the standard output.
|
Echo writes its arguments separated by blanks and terminated by a newline on the standard output. |
|
elvish
Elvish is a cross-platform shell, supporting Linux, BSDs and Windows.
|
Elvish is a cross-platform shell, supporting Linux, BSDs and Windows. |
|
elvish/build
Package build contains build information.
|
Package build contains build information. |
|
elvish/edit
Package edit implements a command line editor.
|
Package edit implements a command line editor. |
|
elvish/edit/eddefs
Package eddefs contains types used in the Editor.
|
Package eddefs contains types used in the Editor. |
|
elvish/edit/highlight
Package highlight implements syntax highlighting for Elvish code.
|
Package highlight implements syntax highlighting for Elvish code. |
|
elvish/edit/location
Package location implements the location mode for the editor.
|
Package location implements the location mode for the editor. |
|
elvish/edit/prompt
Package prompt implements the prompt subsystem of the editor.
|
Package prompt implements the prompt subsystem of the editor. |
|
elvish/edit/tty
Package tty provides terminal functionality for the Elvish editor.
|
Package tty provides terminal functionality for the Elvish editor. |
|
elvish/edit/ui
Package ui contains types that may be used by different editor frontends.
|
Package ui contains types that may be used by different editor frontends. |
|
elvish/eval
Package eval handles evaluation of parsed Elvish code and provides runtime facilities.
|
Package eval handles evaluation of parsed Elvish code and provides runtime facilities. |
|
elvish/eval/bundled
Package bundled keeps bundled modules.
|
Package bundled keeps bundled modules. |
|
elvish/eval/vals
Package vals contains basic facilities for manipulating values used in the Elvish runtime.
|
Package vals contains basic facilities for manipulating values used in the Elvish runtime. |
|
elvish/eval/vars
Package vars contains basic types for manipulating Elvish variables.
|
Package vars contains basic types for manipulating Elvish variables. |
|
elvish/getopt
Package getopt implements a command-line argument parser.
|
Package getopt implements a command-line argument parser. |
|
elvish/glob
Package glob implements globbing for elvish.
|
Package glob implements globbing for elvish. |
|
elvish/parse
Package parse implements the elvish parser.
|
Package parse implements the elvish parser. |
|
elvish/parse/parseutil
Package parseutil contains utilities built on top of the parse package.
|
Package parseutil contains utilities built on top of the parse package. |
|
elvish/program
Package program provides the entry point to Elvish.
|
Package program provides the entry point to Elvish. |
|
elvish/program/shell
Package shell is the entry point for the terminal interface of Elvish.
|
Package shell is the entry point for the terminal interface of Elvish. |
|
elvish/runtime
Package runtime assembles the Elvish runtime.
|
Package runtime assembles the Elvish runtime. |
|
elvish/store/storedefs
Package storedefs contains definitions used by the store package.
|
Package storedefs contains definitions used by the store package. |
|
elvish/sys
Package sys provide convenient wrappers around syscalls.
|
Package sys provide convenient wrappers around syscalls. |
|
elvish/tt
Package tt supports table-driven tests with little boilerplate.
|
Package tt supports table-driven tests with little boilerplate. |
|
elvish/util
Package util contains utility functions.
|
Package util contains utility functions. |
|
false
Returns 1.
|
Returns 1. |
|
field
The `field` command reads newline-separated lines of data from either the standard input or the specified files.
|
The `field` command reads newline-separated lines of data from either the standard input or the specified files. |
|
find
Find finds files.
|
Find finds files. |
|
free
free reports usage information for physical memory and swap space.
|
free reports usage information for physical memory and swap space. |
|
freq
Freq reads the given files (default standard input) and prints histograms of the character frequencies.
|
Freq reads the given files (default standard input) and prints histograms of the character frequencies. |
|
gpgv
gpgv validates a signature against a file.
|
gpgv validates a signature against a file. |
|
gpt
gpt reads and writes GPT headers.
|
gpt reads and writes GPT headers. |
|
grep
Concurrent, parallel grep.
|
Concurrent, parallel grep. |
|
hexdump
Prints files in hexadecimal.
|
Prints files in hexadecimal. |
|
hostname
Print the system's hostname.
|
Print the system's hostname. |
|
id
Synopsis:
|
Synopsis: |
|
init
Build commands in background processes.
|
Build commands in background processes. |
|
insmod
Insert a module into the Linux kernel
|
Insert a module into the Linux kernel |
|
io
io lets you do IO operations.
|
io lets you do IO operations. |
|
kexec
kexec executes a new kernel over the running kernel (u-root).
|
kexec executes a new kernel over the running kernel (u-root). |
|
kill
Kill kills processes.
|
Kill kills processes. |
|
lddfiles
lddfiles prints the arguments and all .so dependencies of those arguments
|
lddfiles prints the arguments and all .so dependencies of those arguments |
|
less
less pages through a file
|
less pages through a file |
|
ln
Ln makes links to files.
|
Ln makes links to files. |
|
losetup
Setup loop devices.
|
Setup loop devices. |
|
ls
Ls prints the contents of a directory.
|
Ls prints the contents of a directory. |
|
lsmod
List modules currently loaded in the Linux kernel
|
List modules currently loaded in the Linux kernel |
|
mkdir
Mkdir makes a new directory.
|
Mkdir makes a new directory. |
|
mkfifo
mkfifo creates a named pipe.
|
mkfifo creates a named pipe. |
|
mknod
Unmount a filesystem at the specified path.
|
Unmount a filesystem at the specified path. |
|
mktemp
Mktemp makes a temporary file (or directory)
|
Mktemp makes a temporary file (or directory) |
|
modprobe
modprobe - Add and remove modules from the Linux Kernel
|
modprobe - Add and remove modules from the Linux Kernel |
|
more
More pages through files without any terminal trickery.
|
More pages through files without any terminal trickery. |
|
mount
Mount a filesystem at the specified path.
|
Mount a filesystem at the specified path. |
|
msr
msr lets you read and write an msr for one or more cores.
|
msr lets you read and write an msr for one or more cores. |
|
mv
Mv renames files and directories.
|
Mv renames files and directories. |
|
netcat
Netcat pipes over the network.
|
Netcat pipes over the network. |
|
ntpdate
simple ntpd daemon in Go.
|
simple ntpd daemon in Go. |
|
pe
Dump the headers of a PE file.
|
Dump the headers of a PE file. |
|
ping
Send icmp packets to a server to test network connectivity.
|
Send icmp packets to a server to test network connectivity. |
|
printenv
Print environment variables.
|
Print environment variables. |
|
ps
Print process information.
|
Print process information. |
|
pwd
Print name of current directory.
|
Print name of current directory. |
|
readlink
readlink display value of symbolic link file.
|
readlink display value of symbolic link file. |
|
rm
Delete files.
|
Delete files. |
|
rmmod
Remove a module from the Linux kernel
|
Remove a module from the Linux kernel |
|
rsdp
rsdp allows to determine the ACPI RSDP structure address which could be passed to the boot command later on It must be executed at the system init as it relies on scanning the kernel messages which could be quickly filled up in some cases
|
rsdp allows to determine the ACPI RSDP structure address which could be passed to the boot command later on It must be executed at the system init as it relies on scanning the kernel messages which could be quickly filled up in some cases |
|
scp
Scp copies files between hosts on a network.
|
Scp copies files between hosts on a network. |
|
seq
Print a sequence of numbers.
|
Print a sequence of numbers. |
|
shutdown
shutdown halts, suspends, or reboots.
|
shutdown halts, suspends, or reboots. |
|
sleep
Delay for the specified amount of time.
|
Delay for the specified amount of time. |
|
sort
Sort lines.
|
Sort lines. |
|
srvfiles
Serve files on the network.
|
Serve files on the network. |
|
strace
strace is a simple single-process tracer.
|
strace is a simple single-process tracer. |
|
strings
Strings finds printable strings.
|
Strings finds printable strings. |
|
stty
The command works like this: stty [verb] [options] Verbs are: dump -- dump the json of the struct to stdout load -- read a json file from stdin and use it to set raw -- convenience command to set raw cooked -- convenience command to set cooked In common stty usage, options may be specified without a verb.
|
The command works like this: stty [verb] [options] Verbs are: dump -- dump the json of the struct to stdout load -- read a json file from stdin and use it to set raw -- convenience command to set raw cooked -- convenience command to set cooked In common stty usage, options may be specified without a verb. |
|
sync
sync command in Go.
|
sync command in Go. |
|
tee
Tee transcribes the standard input to the standard output and makes copies in the files.
|
Tee transcribes the standard input to the standard output and makes copies in the files. |
|
true
Returns 0.
|
Returns 0. |
|
truncate
Truncate - shrink or extend the size of a file to the specified size
|
Truncate - shrink or extend the size of a file to the specified size |
|
umount
Unmount a filesystem at the specified path.
|
Unmount a filesystem at the specified path. |
|
uname
Print build information about the kernel and machine.
|
Print build information about the kernel and machine. |
|
uniq
Uniq removes repeated lines.
|
Uniq removes repeated lines. |
|
unshare
Disassociate parts of the process execution context.
|
Disassociate parts of the process execution context. |
|
validate
This program validates a file by verifying a checksum and a signature file.
|
This program validates a file by verifying a checksum and a signature file. |
|
wc
Wc counts lines, words, runes, syntactically–invalid UTF codes.
|
Wc counts lines, words, runes, syntactically–invalid UTF codes. |
|
wget
Wget reads one file from a url and writes to stdout.
|
Wget reads one file from a url and writes to stdout. |
|
which
Which locates a command.
|
Which locates a command. |
|
examples
|
|
|
uinit
This is a basic init script.
|
This is a basic init script. |
|
pkg
|
|
|
abi
Package abi describes the interface between a kernel and userspace.
|
Package abi describes the interface between a kernel and userspace. |
|
binary
Package binary translates between select fixed-sized types and a binary representation.
|
Package binary translates between select fixed-sized types and a binary representation. |
|
bzimage
package bzImage implements encoding.UnmarshalBinary for bzImage files.
|
package bzImage implements encoding.UnmarshalBinary for bzImage files. |
|
cmdline
The cmdline package provides a parser and convenience functions for reading configuration data from /proc/cmdline it's conformant with https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html, though making 'var_name' and 'var-name' equivalent may need to be done separately.
|
The cmdline package provides a parser and convenience functions for reading configuration data from /proc/cmdline it's conformant with https://www.kernel.org/doc/html/v4.14/admin-guide/kernel-parameters.html, though making 'var_name' and 'var-name' equivalent may need to be done separately. |
|
complete
Package complete implements a simple completion package designed to be used in shells and other programs.
|
Package complete implements a simple completion package designed to be used in shells and other programs. |
|
dhclient
Package dhclient provides a unified interface for interfacing with both DHCPv4 and DHCPv6 clients.
|
Package dhclient provides a unified interface for interfacing with both DHCPv4 and DHCPv6 clients. |
|
dhcp6client
Package dhcp6client implements a DHCPv6 client as per RFC 3315.
|
Package dhcp6client implements a DHCPv6 client as per RFC 3315. |
|
forth
the forth package is designed for use by programs needing to evaluate command-line arguments or simple expressions to set program variables.
|
the forth package is designed for use by programs needing to evaluate command-line arguments or simple expressions to set program variables. |
|
gpt
gpt implements reading and writing of GUID Partition tables.
|
gpt implements reading and writing of GUID Partition tables. |
|
kexecbin
Package kexecbin offers a kexec API via a callout to kexec-tools.
|
Package kexecbin offers a kexec API via a callout to kexec-tools. |
|
ldd
ldd returns all the library dependencies of a list of file names.
|
ldd returns all the library dependencies of a list of file names. |
|
lockfile
Package lockfile coordinates process-based file locking.
|
Package lockfile coordinates process-based file locking. |
|
mount
The mount package implements functions for mounting and unmounting file systems and defines the mount interface.
|
The mount package implements functions for mounting and unmounting file systems and defines the mount interface. |
|
null
Package null extends ioutil.Discard and adds an io.WriteCloser and WriteNameCloser for use within u-root.
|
Package null extends ioutil.Discard and adds an io.WriteCloser and WriteNameCloser for use within u-root. |
|
pty
Package pty provides basic pty support.
|
Package pty provides basic pty support. |
|
pxe
Package pxe aims to implement the PXE specification.
|
Package pxe aims to implement the PXE specification. |
|
qemu
Package qemu is suitable for running QEMU-based integration tests.
|
Package qemu is suitable for running QEMU-based integration tests. |
|
strace
Package strace implements the logic to print out the input and the return value of each traced syscall.
|
Package strace implements the logic to print out the input and the return value of each traced syscall. |
|
termios
Package termios implements basic termios operations including getting a tty struct, termio struct, a winsize struct, and setting raw mode.
|
Package termios implements basic termios operations including getting a tty struct, termio struct, a winsize struct, and setting raw mode. |
|
uroot/util
Package util contains various u-root utility functions.
|
Package util contains various u-root utility functions. |
|
scripts
|
|
|
build_perf
Measure the performance of building all the Go commands under various GOGC values.
|
Measure the performance of building all the Go commands under various GOGC values. |
|
checklicenses
Run with `go run checklicenses.go`.
|
Run with `go run checklicenses.go`. |
|
testramfs
testramfs tests things, badly
|
testramfs tests things, badly |
|
tools
|
|
|
makebb
makebb compiles many Go commands into one bb-style binary.
|
makebb compiles many Go commands into one bb-style binary. |
|
makebbmain
makebbmain creates a bb main.go source file.
|
makebbmain creates a bb main.go source file. |
|
mkinitramfs
mkinitramfs creates a u-root initramfs given the list of files on the command line.
|
mkinitramfs creates a u-root initramfs given the list of files on the command line. |
|
xcmds
|
|
|
archive
Archive archives files.
|
Archive archives files. |
|
ectool
These should all implement io.ReadAt, with the address as the Offset; same for WriteAt.
|
These should all implement io.ReadAt, with the address as the Offset; same for WriteAt. |
|
ed
Options:
|
Options: |
|
forth
Forth is a forth interpreter.
|
Forth is a forth interpreter. |
|
pox
pox builds a portable executable as a squashfs image.
|
pox builds a portable executable as a squashfs image. |
|
run
Run executes its arguments as a Go program.
|
Run executes its arguments as a Go program. |
|
rush
our first builtin: cd
|
our first builtin: cd |
Click to show internal directories.
Click to hide internal directories.