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Yash: yet another shell http://yash.osdn.jp/ ======================= Yash, yet another shell, is a POSIX-compliant command line shell written in C99 (ISO/IEC 9899:1999). Yash is intended to be the most POSIX-compliant shell in the world while supporting features for daily interactive and scripting use. Notable features are: * Global aliases * Arrays * Socket redirection, pipeline redirection, and process redirection * Brace expansion and extended globbing * Fractional numbers in arithmetic expansion * Prompt command and command-not-found handler * Command line completion with predefined completion scripts for more than 100 commands * Command line prediction based on command history Yash can be modified/redistributed under the terms of the GNU General Public License (Version 2) but the use of this program is without any warranty. See the "COPYING" file for the full text of GPL. Yash is an OSDN-hosted project. See also the project summary page at <https://osdn.net/projects/yash/>. ===== Current Development Status ===== Yash now fully supports POSIX.1-2008 (IEEE Std 1003.1, 2016 Edition) except for the limitations listed below. Yash is stable. A maintenance update is released every three months or so. For the change history, see the "NEWS" file. ===== Requirements ===== Yash is supposed to build and run on any POSIX.1-2001 environment with the Software Development Utilities and the C-Language Development Utilities options. Currently, yash is mainly tested on Fedora, macOS, and Cygwin. ===== Installation ===== See the "INSTALL" file to see how to build and install yash. After installation, the manual can be viewed by $ man yash The manual is also available online at <https://yash.osdn.jp/doc/>. ===== Basic Configuration ===== Below is a description of basic configuration that you might want to see after installation to get started with yash. For configuration details, see the manual. --- Initialization scripts --- When yash is started as a login shell, it reads ~/.yash_profile. This file is a shell script in which you define environment variables using the export command. When yash is started for an interactive use, it reads ~/.yashrc (after reading ~/.yash_profile if it is a login shell also). In this file, you make other configurations such as aliases, prompt strings, key bindings for command line editing, and command-not-found handler. Use the "share/initialization/sample" file as a template for your ~/.yashrc. --- Making yash your login shell --- In many Unix-like OSes, a shell must be listed in /etc/shells to be set as a login shell. Edit this file and ensure that the path to yash is written in the file. Then, run the "chsh" command in the terminal and follow instructions from the command. Depending on your system, you may have to use another command to change the login shell. See documentation on your system. ===== Implementation Notes ===== * In C, a null character represents the end of a string. If input to the shell itself contains a null character, characters following the null character will be ignored. * We assume that an overflow in signed integer arithmetic or type conversion silently yields an implementation-defined integer value rather than resulting in an error. * The GCC extension keyword `__attribute__' is used in the source code. When not compiled with GCC, this keyword is removed by the preprocessor, so generally there is no harm. But if your compiler uses this keyword for any other purpose, compilation may fail. Additionally, some other identifiers starting with '_' may cause compilation errors on some rare environments. * Some signals are assumed to have the specific numbers: SIGHUP=1 SIGINT=2 SIGQUIT=3 SIGABRT=6 SIGKILL=9 SIGALRM=14 SIGTERM=15 * POSIX disallows non-interactive shells to ignore or catch SIGTTIN, SIGTTOU, and SIGTSTP by default. Yash, however, ignores these signals if job-control is enabled, even if non-interactive. * File permission flags are assumed to have the specific values: 0400=user read 0200=user write 0100=user execute 0040=group read 0020=group write 0010=group execute 0004=other read 0002=other write 0001=other execute * The character categorization in locales other than the POSIX locale is assumed upward compatible with the POSIX locale. * The -o nolog option is not supported: it is silently ignored. * According to POSIX, the value of variable `PS1' is subject to parameter expansion. Yash performs command substitution and arithmetic expansion as well on the `PS1' value. * According to POSIX, the command `printf %c foo' should print the first byte of string `foo'. Yash prints the first character of `foo', which may be more than one byte. * The "return" built-in, if executed in a trap, can operate only on a function, script, or loop that has been executed within the trap. This limitation is not strictly POSIX-compliant, but needed for consistent and predictable behavior of the shell. * Results of pathname expansion is sorted only by collating sequence of the current locale. If the collating sequence does not have a total ordering of characters, order of uncomparable results are unstable. This limitation is not strictly POSIX-compliant, but inevitable due to use of wide characters in the whole shell. ===== Known Issues ===== * Line number ($LINENO) may not be counted correctly in and after a complex expansion containing a line continuation. * Non-ASCII characters may not be correctly handled in some locales on Solaris. This may be worked around by undefining the HAVE_WCSNRTOMBS macro in the config.h header file. ===== Contributions ===== Comments, suggestions, and bug reports are welcome at: * Issue tracking system <https://osdn.net/projects/yash/ticket/> * Discussion forum <https://osdn.net/projects/yash/forums/> If you are interested in translation, please refer to <https://osdn.net/projects/yash/wiki/HowToTranslate>. ====================== Watanabe, Yuki <email@example.com>