# OpenWrt XBurst Git Source Tree

## Root/docs/build.tex

 1 One of the biggest challenges to getting started with embedded devices is that you 2 cannot just install a copy of Linux and expect to be able to compile a firmware. 3 Even if you did remember to install a compiler and every development tool offered, 4 you still would not have the basic set of tools needed to produce a firmware image. 5 The embedded device represents an entirely new hardware platform, which is 6 most of the time incompatible with the hardware on your development machine, so in a process called 7 cross compiling you need to produce a new compiler capable of generating code for 8 your embedded platform, and then use it to compile a basic Linux distribution to 9 run on your device. 10 11 The process of creating a cross compiler can be tricky, it is not something that is 12 regularly attempted and so there is a certain amount of mystery and black magic 13 associated with it. In many cases when you are dealing with embedded devices you will 14 be provided with a binary copy of a compiler and basic libraries rather than 15 instructions for creating your own -- it is a time saving step but at the same time 16 often means you will be using a rather dated set of tools. Likewise, it is also common 17 to be provided with a patched copy of the Linux kernel from the board or chip vendor, 18 but this is also dated and it can be difficult to spot exactly what has been 19 modified to make the kernel run on the embedded platform. 20 21 \subsection{Building an image} 22 23 OpenWrt takes a different approach to building a firmware; downloading, patching 24 and compiling everything from scratch, including the cross compiler. To put it 25 in simpler terms, OpenWrt does not contain any executables or even sources, it is an 26 automated system for downloading the sources, patching them to work with the given 27 platform and compiling them correctly for that platform. What this means is that 28 just by changing the template, you can change any step in the process. 29 30 As an example, if a new kernel is released, a simple change to one of the Makefiles 31 will download the latest kernel, patch it to run on the embedded platform and produce 32 a new firmware image -- there is no work to be done trying to track down an unmodified 33 copy of the existing kernel to see what changes had been made, the patches are 34 already provided and the process ends up almost completely transparent. This does not 35 just apply to the kernel, but to anything included with OpenWrt -- It is this one 36 simple understated concept which is what allows OpenWrt to stay on the bleeding edge 37 with the latest compilers, latest kernels and latest applications. 38 39 So let's take a look at OpenWrt and see how this all works. 40 41 42 \subsubsection{Download OpenWrt} 43 44 OpenWrt can be downloaded via subversion using the following command: 45 46 \begin{Verbatim} 47 $svn checkout svn://svn.openwrt.org/openwrt/trunk openwrt-trunk 48 \end{Verbatim} 49 50 Additionally, there is a trac interface on \href{https://dev.openwrt.org/}{https://dev.openwrt.org/} 51 which can be used to monitor svn commits and browse the source repository. 52 53 54 \subsubsection{The directory structure} 55 56 There are four key directories in the base: 57 58 \begin{itemize} 59 \item \texttt{tools} 60 \item \texttt{toolchain} 61 \item \texttt{package} 62 \item \texttt{target} 63 \end{itemize} 64 65 \texttt{tools} and \texttt{toolchain} refer to common tools which will be 66 used to build the firmware image, the compiler, and the C library. 67 The result of this is three new directories, \texttt{build\_dir/host}, which is a temporary 68 directory for building the target independent tools, \texttt{build\_dir/toolchain-\textit{}*} 69 which is used for building the toolchain for a specific architecture, and 70 \texttt{staging\_dir/toolchain-\textit{}*} where the resulting toolchain is installed. 71 You will not need to do anything with the toolchain directory unless you intend to 72 add a new version of one of the components above. 73 74 \begin{itemize} 75 \item \texttt{build\_dir/host} 76 \item \texttt{build\_dir/toolchain-\textit{}*} 77 \end{itemize} 78 79 \texttt{package} is for exactly that -- packages. In an OpenWrt firmware, almost everything 80 is an \texttt{.ipk}, a software package which can be added to the firmware to provide new 81 features or removed to save space. Note that packages are also maintained outside of the main 82 trunk and can be obtained from subversion using the package feeds system: 83 84 \begin{Verbatim} 85$ ./scripts/feeds update 86 \end{Verbatim} 87 88 Those packages can be used to extend the functionality of the build system and need to be 89 symlinked into the main trunk. Once you do that, the packages will show up in the menu for 90 configuration. You would do something like this: 91 92 \begin{Verbatim} 93 $./scripts/feeds search nmap 94 Search results in feed 'packages': 95 nmap Network exploration and/or security auditing utility 96 97$ ./scripts/feeds install nmap 98 \end{Verbatim} 99 100 To include all packages, issue the following command: 101 102 \begin{Verbatim} 103 $make package/symlinks 104 \end{Verbatim} 105 106 \texttt{target} refers to the embedded platform, this contains items which are specific to 107 a specific embedded platform. Of particular interest here is the "\texttt{target/linux}" 108 directory which is broken down by platform \textit{} and contains the patches to the 109 kernel, profile config, for a particular platform. There's also the "\texttt{target/image}" directory 110 which describes how to package a firmware for a specific platform. 111 112 Both the target and package steps will use the directory "\texttt{build\_dir/\textit{}}" 113 as a temporary directory for compiling. Additionally, anything downloaded by the toolchain, 114 target or package steps will be placed in the "\texttt{dl}" directory. 115 116 \begin{itemize} 117 \item \texttt{build\_dir/\textit{}} 118 \item \texttt{dl} 119 \end{itemize} 120 121 \subsubsection{Building OpenWrt} 122 123 While the OpenWrt build environment was intended mostly for developers, it also has to be 124 simple enough that an inexperienced end user can easily build his or her own customized firmware. 125 126 Running the command "\texttt{make menuconfig}" will bring up OpenWrt's configuration menu 127 screen, through this menu you can select which platform you're targeting, which versions of 128 the toolchain you want to use to build and what packages you want to install into the 129 firmware image. Note that it will also check to make sure you have the basic dependencies for it 130 to run correctly. If that fails, you will need to install some more tools in your local environment 131 before you can begin. 132 133 Similar to the linux kernel config, almost every option has three choices, 134 \texttt{y/m/n} which are represented as follows: 135 136 \begin{itemize} 137 \item{\texttt{<*>} (pressing y)} \\ 138 This will be included in the firmware image 139 \item{\texttt{} (pressing m)} \\ 140 This will be compiled but not included (for later install) 141 \item{\texttt{< >} (pressing n)} \\ 142 This will not be compiled 143 \end{itemize} 144 145 After you've finished with the menu configuration, exit and when prompted, save your 146 configuration changes. 147 148 If you want, you can also modify the kernel config for the selected target system. 149 simply run "\texttt{make kernel\_menuconfig}" and the build system will unpack the kernel sources 150 (if necessary), run menuconfig inside of the kernel tree, and then copy the kernel config 151 to \texttt{target/linux/\textit{}/config} so that it is preserved over 152 "\texttt{make clean}" calls. 153 154 To begin compiling the firmware, type "\texttt{make}". By default 155 OpenWrt will only display a high level overview of the compile process and not each individual 156 command. 157 158 \subsubsection{Example:} 159 160 \begin{Verbatim} 161 make[2] toolchain/install 162 make[3] -C toolchain install 163 make[2] target/compile 164 make[3] -C target compile 165 make[4] -C target/utils prepare 166 167 [...] 168 \end{Verbatim} 169 170 This makes it easier to monitor which step it's actually compiling and reduces the amount 171 of noise caused by the compile output. To see the full output, run the command 172 "\texttt{make V=99}". 173 174 During the build process, buildroot will download all sources to the "\texttt{dl}" 175 directory and will start patching and compiling them in the "\texttt{build\_dir/\textit{}}" 176 directory. When finished, the resulting firmware will be in the "\texttt{bin}" directory 177 and packages will be in the "\texttt{bin/packages}" directory. 178 179 180 \subsection{Creating packages} 181 182 One of the things that we've attempted to do with OpenWrt's template system is make it 183 incredibly easy to port software to OpenWrt. If you look at a typical package directory 184 in OpenWrt you'll find several things: 185 186 \begin{itemize} 187 \item \texttt{package/\textit{}/Makefile} 188 \item \texttt{package/\textit{}/patches} 189 \item \texttt{package/\textit{}/files} 190 \end{itemize} 191 192 The patches directory is optional and typically contains bug fixes or optimizations to 193 reduce the size of the executable. The package makefile is the important item, provides 194 the steps actually needed to download and compile the package. 195 196 The files directory is also optional and typicall contains package specific startup scripts or default configuration files that can be used out of the box with OpenWrt. 197 198 Looking at one of the package makefiles, you'd hardly recognize it as a makefile. 199 Through what can only be described as blatant disregard and abuse of the traditional 200 make format, the makefile has been transformed into an object oriented template which 201 simplifies the entire ordeal. 202 203 Here for example, is \texttt{package/bridge/Makefile}: 204 205 \begin{Verbatim}[frame=single,numbers=left] 206 207 include$(TOPDIR)/rules.mk 208 209 PKG_NAME:=bridge 210 PKG_VERSION:=1.0.6 211 PKG_RELEASE:=1 212 213 PKG_SOURCE:=bridge-utils-$(PKG_VERSION).tar.gz 214 PKG_SOURCE_URL:=@SF/bridge 215 PKG_MD5SUM:=9b7dc52656f5cbec846a7ba3299f73bd 216 PKG_CAT:=zcat 217 218 PKG_BUILD_DIR:=$(BUILD_DIR)/bridge-utils-$(PKG_VERSION) 219 220 include$(INCLUDE_DIR)/package.mk 221 222 define Package/bridge 223 SECTION:=net 224 CATEGORY:=Base system 225 TITLE:=Ethernet bridging configuration utility 226 URL:=http://bridge.sourceforge.net/ 227 endef 228 229 define Package/bridge/description 230 Manage ethernet bridging: 231 a way to connect networks together to form a larger network. 232 endef 233 234 define Build/Configure 235 $(call Build/Configure/Default, \ 236 --with-linux-headers="$(LINUX_DIR)" \ 237 ) 238 endef 239 240 define Package/bridge/install 241 $(INSTALL_DIR)$(1)/usr/sbin 242 $(INSTALL_BIN)$(PKG_BUILD_DIR)/brctl/brctl $(1)/usr/sbin/ 243 endef 244 245$(eval $(call BuildPackage,bridge)) 246 \end{Verbatim} 247 248 As you can see, there's not much work to be done; everything is hidden in other makefiles 249 and abstracted to the point where you only need to specify a few variables. 250 251 \begin{itemize} 252 \item \texttt{PKG\_NAME} \\ 253 The name of the package, as seen via menuconfig and ipkg 254 \item \texttt{PKG\_VERSION} \\ 255 The upstream version number that we are downloading 256 \item \texttt{PKG\_RELEASE} \\ 257 The version of this package Makefile 258 \item \texttt{PKG\_SOURCE} \\ 259 The filename of the original sources 260 \item \texttt{PKG\_SOURCE\_URL} \\ 261 Where to download the sources from (no trailing slash), you can add multiple download sources by separating them with a \\ and a carriage return. 262 \item \texttt{PKG\_MD5SUM} \\ 263 A checksum to validate the download 264 \item \texttt{PKG\_CAT} \\ 265 How to decompress the sources (zcat, bzcat, unzip) 266 \item \texttt{PKG\_BUILD\_DIR} \\ 267 Where to compile the package 268 \end{itemize} 269 270 The \texttt{PKG\_*} variables define where to download the package from; 271 \texttt{@SF} is a special keyword for downloading packages from sourceforge. There is also 272 another keyword of \texttt{@GNU} for grabbing GNU source releases. If any of the above mentionned download source fails, the OpenWrt mirrors will be used as source. 273 274 The md5sum (if present) is used to verify the package was downloaded correctly and 275 \texttt{PKG\_BUILD\_DIR} defines where to find the package after the sources are 276 uncompressed into \texttt{\$(BUILD\_DIR)}. 277 278 At the bottom of the file is where the real magic happens, "BuildPackage" is a macro 279 set up by the earlier include statements. BuildPackage only takes one argument directly -- 280 the name of the package to be built, in this case "\texttt{bridge}". All other information 281 is taken from the define blocks. This is a way of providing a level of verbosity, it's 282 inherently clear what the contents of the \texttt{description} template in 283 \texttt{Package/bridge} is, which wouldn't be the case if we passed this information 284 directly as the Nth argument to \texttt{BuildPackage}. 285 286 \texttt{BuildPackage} uses the following defines: 287 288 \textbf{\texttt{Package/\textit{}}:} \\ 289 \texttt{\textit{}} matches the argument passed to buildroot, this describes 290 the package the menuconfig and ipkg entries. Within \texttt{Package/\textit{}} 291 you can define the following variables: 292 293 \begin{itemize} 294 \item \texttt{SECTION} \\ 295 The section of package (currently unused) 296 \item \texttt{CATEGORY} \\ 297 Which menu it appears in menuconfig: Network, Sound, Utilities, Multimedia ... 298 \item \texttt{TITLE} \\ 299 A short description of the package 300 \item \texttt{URL} \\ 301 Where to find the original software 302 \item \texttt{MAINTAINER} (optional) \\ 303 Who to contact concerning the package 304 \item \texttt{DEPENDS} (optional) \\ 305 Which packages must be built/installed before this package. To reference a dependency defined in the 306 same Makefile, use \textit{}. If defined as an external package, use 307 \textit{+}. For a kernel version dependency use: \textit{@LINUX\_2\_} 308 \item \texttt{BUILDONLY} (optional) \\ 309 Set this option to 1 if you do NOT want your package to appear in menuconfig. 310 This is useful for packages which are only used as build dependencies. 311 \end{itemize} 312 313 \textbf{\texttt{Package/\textit{}/conffiles} (optional):} \\ 314 A list of config files installed by this package, one file per line. 315 316 \textbf{\texttt{Build/Prepare} (optional):} \\ 317 A set of commands to unpack and patch the sources. You may safely leave this 318 undefined. 319 320 \textbf{\texttt{Build/Configure} (optional):} \\ 321 You can leave this undefined if the source doesn't use configure or has a 322 normal config script, otherwise you can put your own commands here or use 323 "\texttt{\$(call Build/Configure/Default,\textit{})}" as above to 324 pass in additional arguments for a standard configure script. The first list of arguments will be passed 325 to the configure script like that: \texttt{--arg 1} \texttt{--arg 2}. The second list contains arguments that should be 326 defined before running the configure script such as autoconf or compiler specific variables. 327 328 To make it easier to modify the configure command line, you can either extend or completely override the following variables: 329 \begin{itemize} 330 \item \texttt{CONFIGURE\_ARGS} \\ 331 Contains all command line arguments (format: \texttt{--arg 1} \texttt{--arg 2}) 332 \item \texttt{CONFIGURE\_VARS} \\ 333 Contains all environment variables that are passed to ./configure (format: \texttt{NAME="value"}) 334 \end{itemize} 335 336 \textbf{\texttt{Build/Compile} (optional):} \\ 337 How to compile the source; in most cases you should leave this undefined. 338 339 As with \texttt{Build/Configure} there are two variables that allow you to override 340 the make command line environment variables and flags: 341 \begin{itemize} 342 \item \texttt{MAKE\_FLAGS} \\ 343 Contains all command line arguments (typically variable overrides like \texttt{NAME="value"} 344 \item \texttt{MAKE\_VARS} \\ 345 Contains all environment variables that are passed to the make command 346 \end{itemize} 347 348 \textbf{\texttt{Build/InstallDev} (optional):} \\ 349 If your package provides a library that needs to be made available to other packages, 350 you can use the \texttt{Build/InstallDev} template to copy it into the staging directory 351 which is used to collect all files that other packages might depend on at build time. 352 When it is called by the build system, two parameters are passed to it. \texttt{\$(1)} points to 353 the regular staging dir, typically \texttt{staging\_dir/\textit{ARCH}}, while \texttt{\$(2)} points 354 to \texttt{staging\_dir/host}. The host staging dir is only used for binaries, which are 355 to be executed or linked against on the host and its \texttt{bin/} subdirectory is included 356 in the \texttt{PATH} which is passed down to the build system processes. 357 Please use \texttt{\$(1)} and \texttt{\$(2)} here instead of the build system variables 358 \texttt{\$(STAGING\_DIR)} and \texttt{\$(STAGING\_DIR\_HOST)}, because the build system behavior 359 when staging libraries might change in the future to include automatic uninstallation. 360 361 \textbf{\texttt{Package/\textit{}/install}:} \\ 362 A set of commands to copy files out of the compiled source and into the ipkg 363 which is represented by the \texttt{\$(1)} directory. Note that there are currently 364 4 defined install macros: 365 \begin{itemize} 366 \item \texttt{INSTALL\_DIR} \\ 367 install -d -m0755 368 \item \texttt{INSTALL\_BIN} \\ 369 install -m0755 370 \item \texttt{INSTALL\_DATA} \\ 371 install -m0644 372 \item \texttt{INSTALL\_CONF} \\ 373 install -m0600 374 \end{itemize} 375 376 The reason that some of the defines are prefixed by "\texttt{Package/\textit{}}" 377 and others are simply "\texttt{Build}" is because of the possibility of generating 378 multiple packages from a single source. OpenWrt works under the assumption of one 379 source per package Makefile, but you can split that source into as many packages as 380 desired. Since you only need to compile the sources once, there's one global set of 381 "\texttt{Build}" defines, but you can add as many "Package/" defines as you want 382 by adding extra calls to \texttt{BuildPackage} -- see the dropbear package for an example. 383 384 After you have created your \texttt{package/\textit{}/Makefile}, the new package 385 will automatically show in the menu the next time you run "make menuconfig" and if selected 386 will be built automatically the next time "\texttt{make}" is run. 387 388 \subsection{Creating binary packages} 389 390 You might want to create binary packages and include them in the resulting images as packages. 391 To do so, you can use the following template, which basically sets to nothing the Configure and 392 Compile templates. 393 394 \begin{Verbatim}[frame=single,numbers=left] 395 396 include $(TOPDIR)/rules.mk 397 398 PKG_NAME:=binpkg 399 PKG_VERSION:=1.0 400 PKG_RELEASE:=1 401 402 PKG_SOURCE:=binpkg-$(PKG_VERSION).tar.gz 403 PKG_SOURCE_URL:=http://server 404 PKG_MD5SUM:=9b7dc52656f5cbec846a7ba3299f73bd 405 PKG_CAT:=zcat 406 407 include $(INCLUDE_DIR)/package.mk 408 409 define Package/binpkg 410 SECTION:=net 411 CATEGORY:=Network 412 TITLE:=Binary package 413 endef 414 415 define Package/bridge/description 416 Binary package 417 endef 418 419 define Build/Configure 420 endef 421 422 define Build/Compile 423 endef 424 425 define Package/bridge/install 426$(INSTALL_DIR) $(1)/usr/sbin 427$(INSTALL_BIN) $(PKG_BUILD_DIR)/*$(1)/usr/sbin/ 428 endef 429 430 $(eval$(call BuildPackage,bridge)) 431 \end{Verbatim} 432 433 Provided that the tarball which contains the binaries reflects the final 434 directory layout (/usr, /lib ...), it becomes very easy to get your package 435 look like one build from sources. 436 437 Note that using the same technique, you can easily create binary pcakages 438 for your proprietary kernel modules as well. 439 440 \subsection{Creating kernel modules packages} 441 442 The OpenWrt distribution makes the distinction between two kind of kernel modules, those coming along with the mainline kernel, and the others available as a separate project. We will see later that a common template is used for both of them. 443 444 For kernel modules that are part of the mainline kernel source, the makefiles are located in \textit{package/kernel/modules/*.mk} and they appear under the section "Kernel modules" 445 446 For external kernel modules, you can add them to the build system just like if they were software packages by defining a KernelPackage section in the package makefile. 447 448 Here for instance the Makefile for the I2C subsytem kernel modules : 449 450 \begin{Verbatim}[frame=single,numbers=left] 451 452 I2CMENU:=I2C Bus 453 454 define KernelPackage/i2c-core 455 TITLE:=I2C support 456 DESCRIPTION:=Kernel modules for i2c support 457 SUBMENU:=$(I2CMENU) 458 KCONFIG:=CONFIG_I2C_CORE CONFIG_I2C_DEV 459 FILES:=$(MODULES_DIR)/kernel/drivers/i2c/*.$(LINUX_KMOD_SUFFIX) 460 AUTOLOAD:=$(call AutoLoad,50,i2c-core i2c-dev) 461 endef 462 $(eval$(call KernelPackage,i2c-core)) 463 \end{Verbatim} 464 465 To group kernel modules under a common description in menuconfig, you might want to define a \textit{MENU} variable on top of the kernel modules makefile. 466 467 \begin{itemize} 468 \item \texttt{TITLE} \\ 469 The name of the module as seen via menuconfig 470 \item \texttt{DESCRIPTION} \\ 471 The description as seen via help in menuconfig 472 \item \texttt{SUBMENU} \\ 473 The sub menu under which this package will be seen 474 \item \texttt{KCONFIG} \\ 475 Kernel configuration option dependency. For external modules, remove it. 476 \item \texttt{FILES} \\ 477 Files you want to inlude to this kernel module package, separate with spaces. 478 \item \texttt{AUTOLOAD} \\ 479 Modules that will be loaded automatically on boot, the order you write them is the order they would be loaded. 480 \end{itemize} 481 482 After you have created your \texttt{package/kernel/modules/\textit{}.mk}, the new kernel modules package 483 will automatically show in the menu under "Kernel modules" next time you run "make menuconfig" and if selected 484 will be built automatically the next time "\texttt{make}" is run. 485 486 \subsection{Conventions} 487 488 There are a couple conventions to follow regarding packages: 489 490 \begin{itemize} 491 \item \texttt{files} 492 \begin{enumerate} 493 \item configuration files follow the convention \\ 494 \texttt{\textit{}.conf} 495 \item init files follow the convention \\ 496 \texttt{\textit{}.init} 497 \end{enumerate} 498 \item \texttt{patches} 499 \begin{enumerate} 500 \item patches are numerically prefixed and named related to what they do 501 \end{enumerate} 502 \end{itemize} 503 504 \subsection{Troubleshooting} 505 506 If you find your package doesn't show up in menuconfig, try the following command to 507 see if you get the correct description: 508 509 \begin{Verbatim} 510 TOPDIR=\$PWD make -C package/ DUMP=1 V=99 511 \end{Verbatim} 512 513 If you're just having trouble getting your package to compile, there's a few 514 shortcuts you can take. Instead of waiting for make to get to your package, you can 515 run one of the following: 516 517 \begin{itemize} 518 \item \texttt{make package/\textit{}/clean V=99} 519 \item \texttt{make package/\textit{}/install V=99} 520 \end{itemize} 521 522 Another nice trick is that if the source directory under \texttt{build\_dir/\textit{}} 523 is newer than the package directory, it won't clobber it by unpacking the sources again. 524 If you were working on a patch you could simply edit the sources under the 525 \texttt{build\_dir/\textit{}/\textit{}} directory and run the install command above, 526 when satisfied, copy the patched sources elsewhere and diff them with the unpatched 527 sources. A warning though - if you go modify anything under \texttt{package/\textit{}} 528 it will remove the old sources and unpack a fresh copy. 529 530 Other useful targets include: 531 532 \begin{itemize} 533 \item \texttt{make package/\textit{}/prepare V=99} 534 \item \texttt{make package/\textit{}/compile V=99} 535 \item \texttt{make package/\textit{}/configure V=99} 536 \end{itemize} 537 538 539 \subsection{Using build environments} 540 OpenWrt provides a means of building images for multiple configurations 541 which can use multiple targets in one single checkout. These \emph{environments} 542 store a copy of the .config file generated by \texttt{make menuconfig} and the contents 543 of the \texttt{./files} folder. 544 The script \texttt{./scripts/env} is used to manage these environments, it uses 545 \texttt{git} (which needs to be installed on your system) as backend for version control. 546 547 The command 548 \begin{Verbatim} 549 ./scripts/env help 550 \end{Verbatim} 551 produces a short help text with a list of commands. 552 553 To create a new environment named \texttt{current}, run the following command 554 \begin{Verbatim} 555 ./scripts/env new current 556 \end{Verbatim} 557 This will move your \texttt{.config} file and \texttt{./files} (if it exists) to 558 the \texttt{env/} subdirectory and create symlinks in the base folder. 559 560 After running make menuconfig or changing things in files/, your current state will 561 differ from what has been saved before. To show these changes, use: 562 \begin{Verbatim} 563 ./scripts/env diff 564 \end{Verbatim} 565 566 If you want to save these changes, run: 567 \begin{Verbatim} 568 ./scripts/env save 569 \end{Verbatim} 570 If you want to revert your changes to the previously saved copy, run: 571 \begin{Verbatim} 572 ./scripts/env revert 573 \end{Verbatim} 574 575 If you want, you can now create a second environment using the \texttt{new} command. 576 It will ask you whether you want to make it a clone of the current environment (e.g. 577 for minor changes) or if you want to start with a clean version (e.g. for selecting 578 a new target). 579 580 To switch to a different environment (e.g. \texttt{test1}), use: 581 \begin{Verbatim} 582 ./scripts/env switch test1 583 \end{Verbatim} 584 585 To rename the current branch to a new name (e.g. \texttt{test2}), use: 586 \begin{Verbatim} 587 ./scripts/env rename test2 588 \end{Verbatim} 589 590 If you want to get rid of environment switching and keep everything in the base directory 591 again, use: 592 \begin{Verbatim} 593 ./scripts/env clear 594 \end{Verbatim} 595