X-Git-Url: http://review.tizen.org/git/?a=blobdiff_plain;f=doc%2FFAQ;h=1fafa6df34b08e9c73e00a99abec39b4caebdcb4;hb=28ef6c316f1aff914bb95ac09787a3c83c1815fd;hp=d191cb4e16b738085f5252e26cd1d85a4e853b30;hpb=bc4cd23ce958feda898c618215f94d8a4e8f4ffa;p=platform%2Fupstream%2Fbash.git diff --git a/doc/FAQ b/doc/FAQ index d191cb4..1fafa6d 100644 --- a/doc/FAQ +++ b/doc/FAQ @@ -1,4 +1,4 @@ -This is the Bash FAQ, version 2.13, for Bash version 2.02. +This is the Bash FAQ, version 3.11, for Bash version 2.05. This document contains a set of frequently-asked questions concerning Bash, the GNU Bourne-Again Shell. Bash is a freely-available command @@ -15,92 +15,106 @@ This document is available for anonymous FTP with the URL ftp://ftp.cwru.edu/pub/bash/FAQ +The Bash home page is http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html + ---------- Contents: Section A: The Basics -1) What is it? -2) What's the latest version? -3) Where can I get it? -4) On what machines will bash run? -5) Will bash run on operating systems other than Unix? -6) How can I build bash with gcc? -7) How can I make bash my login shell? -8) I just changed my login shell to bash, and now I can't FTP into my - machine. Why not? -9) What's the `POSIX 1003.2 standard'? -10) What is the bash `posix mode'? +A1) What is it? +A2) What's the latest version? +A3) Where can I get it? +A4) On what machines will bash run? +A5) Will bash run on operating systems other than Unix? +A6) How can I build bash with gcc? +A7) How can I make bash my login shell? +A8) I just changed my login shell to bash, and now I can't FTP into my + machine. Why not? +A9) What's the `POSIX 1003.2 standard'? +A10) What is the bash `posix mode'? Section B: The latest version -11) What's new in version 2.02? -12) Are there any user-visible incompatibilities between bash-2.02 and +B1) What's new in version 2.05? +B2) Are there any user-visible incompatibilities between bash-2.05 and bash-1.14.7? Section C: Differences from other Unix shells -13) How does bash differ from sh, the Bourne shell? -14) How does bash differ from the Korn shell, version ksh88? -15) Which new features in ksh-93 are not in bash, and which are? +C1) How does bash differ from sh, the Bourne shell? +C2) How does bash differ from the Korn shell, version ksh88? +C3) Which new features in ksh-93 are not in bash, and which are? Section D: Why does bash do some things differently than other Unix shells? -16) Why does bash run a different version of `command' than +D1) Why does bash run a different version of `command' than `which command' says it will? -17) Why doesn't bash treat brace expansions exactly like csh? -18) Why doesn't bash have csh variable modifiers? -19) How can I make my csh aliases work when I convert to bash? -20) How can I pipe standard output and standard error from one command to +D2) Why doesn't bash treat brace expansions exactly like csh? +D3) Why doesn't bash have csh variable modifiers? +D4) How can I make my csh aliases work when I convert to bash? +D5) How can I pipe standard output and standard error from one command to another, like csh does with `|&'? -21) Now that I've converted from ksh to bash, are there equivalents to +D6) Now that I've converted from ksh to bash, are there equivalents to ksh features like autoloaded functions and the `whence' command? -Section E: How can I get bash to do certain things, and why does bash do - things the way it does? +Section E: Why does bash do certain things the way it does? -22) Why is the bash builtin `test' slightly different from /bin/test? -23) Why does bash sometimes say `Broken pipe'? -24) How can I get bash to read and display eight-bit characters? -25) How do I write a function `x' to replace builtin command `x', but - still invoke the command from within the function? -26) When I have terminal escape sequences in my prompt, why does bash +E1) Why is the bash builtin `test' slightly different from /bin/test? +E2) Why does bash sometimes say `Broken pipe'? +E3) When I have terminal escape sequences in my prompt, why does bash wrap lines at the wrong column? -27) How can I find the value of a shell variable whose name is the value - of another shell variable? -28) If I pipe the output of a command into `read variable', why doesn't +E4) If I pipe the output of a command into `read variable', why doesn't the output show up in $variable when the read command finishes? -29) I have a bunch of shell scripts that use backslash-escaped characters +E5) I have a bunch of shell scripts that use backslash-escaped characters in arguments to `echo'. Bash doesn't interpret these characters. Why not, and how can I make it understand them? -30) Why doesn't a while or for loop get suspended when I type ^Z? -31) How can I make the bash `time' reserved word print timing output that - looks like the output from my system's /usr/bin/time? +E6) Why doesn't a while or for loop get suspended when I type ^Z? +E7) What about empty for loops in Makefiles? +E8) Why does the arithmetic evaluation code complain about `08'? +E9) Why does the pattern matching expression [A-Z]* match files beginning + with every letter except `z'? Section F: Things to watch out for on certain Unix versions -32) Why can't I use command line editing in my `cmdtool'? -33) I built bash on Solaris 2. Why do globbing expansions and filename +F1) Why can't I use command line editing in my `cmdtool'? +F2) I built bash on Solaris 2. Why do globbing expansions and filename completion chop off the first few characters of each filename? -34) Why does bash dump core after I interrupt username completion or +F3) Why does bash dump core after I interrupt username completion or `~user' tilde expansion on a machine running NIS? -35) I'm running SVR4.2. Why is the line erased every time I type `@'? -36) Why does bash report syntax errors when my C News scripts use a +F4) I'm running SVR4.2. Why is the line erased every time I type `@'? +F5) Why does bash report syntax errors when my C News scripts use a redirection before a subshell command? +F6) Why can't I use vi-mode editing on Red Hat Linux 6.1? + +Section G: How can I get bash to do certain common things? + +G1) How can I get bash to read and display eight-bit characters? +G2) How do I write a function `x' to replace builtin command `x', but + still invoke the command from within the function? +G3) How can I find the value of a shell variable whose name is the value + of another shell variable? +G4) How can I make the bash `time' reserved word print timing output that + looks like the output from my system's /usr/bin/time? +G5) How do I get the current directory into my prompt? +G6) How can I rename "*.foo" to "*.bar"? +G7) How can I translate a filename from uppercase to lowercase? +G8) How can I write a filename expansion (globbing) pattern that will match + all files in the current directory except "." and ".."? -Section G: Where do I go from here? +Section H: Where do I go from here? -37) How do I report bugs in bash, and where should I look for fixes and +H1) How do I report bugs in bash, and where should I look for fixes and advice? -38) What kind of bash documentation is there? -39) What's coming in future versions? -40) What's on the bash `wish list'? -41) When will the next release appear? +H2) What kind of bash documentation is there? +H3) What's coming in future versions? +H4) What's on the bash `wish list'? +H5) When will the next release appear? ---------- Section A: The Basics -1) What is it? +A1) What is it? Bash is a Unix command interpreter (shell). It is an implementation of the Posix 1003.2 shell standard, and resembles the Korn and System V @@ -118,26 +132,26 @@ Bash was originally written by Brian Fox of the Free Software Foundation. The current developer and maintainer is Chet Ramey of Case Western Reserve University. -2) What's the latest version? +A2) What's the latest version? -The latest version is 2.02, first made available on Monday, 20 April, 1998. +The latest version is 2.05, first made available on Monday, 9 April 2001. -3) Where can I get it? +A3) Where can I get it? Bash is the GNU project's shell, and so is available from the -master GNU archive site, prep.ai.mit.edu, and its mirrors. The +master GNU archive site, ftp.gnu.org, and its mirrors. The latest version is also available for FTP from ftp.cwru.edu. -The following URLs tell how to get version 2.02: +The following URLs tell how to get version 2.05: -ftp://prep.ai.mit.edu/pub/gnu/bash-2.02.tar.gz -ftp://ftp.cwru.edu/pub/bash/bash-2.02.tar.gz +ftp://ftp.gnu.org/pub/gnu/bash/bash-2.05.tar.gz +ftp://ftp.cwru.edu/pub/bash/bash-2.05.tar.gz Formatted versions of the documentation are available with the URLs: -ftp://prep.ai.mit.edu/pub/gnu/bash-doc-2.02.tar.gz -ftp://ftp.cwru.edu/pub/bash/bash-doc-2.02.tar.gz +ftp://ftp.gnu.org/pub/gnu/bash/bash-doc-2.05.tar.gz +ftp://ftp.cwru.edu/pub/bash/bash-doc-2.05.tar.gz -4) On what machines will bash run? +A4) On what machines will bash run? Bash has been ported to nearly every version of UNIX. All you should have to do to build it on a machine for which a port @@ -147,43 +161,42 @@ itself accordingly, using a script created by GNU autoconf. More information appears in the file `INSTALL' in the distribution. -5) Will bash run on operating systems other than Unix? +A5) Will bash run on operating systems other than Unix? Configuration specifics for Unix-like systems such as QNX and -LynxOS are included in the distribution. Bash-2.02 should +LynxOS are included in the distribution. Bash-2.05 should compile and run on Minix 2.0 (patches were contributed), but I don't believe anyone has built bash-2.x on earlier Minix versions yet. Bash has been ported to versions of Windows implementing the Win32 programming interface. This includes Windows 95 and Windows NT. -The port was done by Cygnus Solutions as part of their GNU-Win32 -project. For more information about the project, look at the URL +The port was done by Cygnus Solutions as part of their CYGWIN +project. For more information about the project, look at the URLs -http://www.cygnus.com/misc/gnu-win32 +http://www.cygwin.com/ +http://sourceware.cygnus.com/cygwin -Cygnus has ported bash-1.14.7, and their port is part of the current -gnu-win32 release. Cygnus has also done a port of bash-2.01 to the -GNU-Win32 environment, and it should be available as part of their next -release. +Cygnus originally ported bash-1.14.7, and that port was part of their +early GNU-Win32 (the original name) releases. Cygnus has also done a +port of bash-2.04 to the CYGWIN environment, and it is available as +part of their current release. -Bash-2.02 should require no local Cygnus changes to build and run under -GNU-WIN32. +Bash-2.05 should require no local Cygnus changes to build and run under +CYGWIN. The Cygnus port works only on Intel machines. There is a port of bash (I don't know which version) to the alpha/NT environment available from ftp://ftp.gnustep.org//pub/win32/bash-alpha-nt-1.01.tar.gz -Softway Systems has ported bash-2.01.1 to their Interix (nee OpenNT) -system, a Unix subsystem for NT that replaces the Microsoft POSIX -subsystem. Check out http://www.interix.com for more information. - -D. J. Delorie has ported bash-1.14.7 to run under MS-DOS, as part of -the DJGPP project. For more information on the project, see +DJ Delorie has a port of bash-1.14.7 which runs under MS-DOS, as part +of the DJGPP project. For more information on the project, see http://www.delorie.com/djgpp/ +I have been told that the original DJGPP port was done by Daisuke Aoyama. + I picked up a binary of bash-1.14.7 that is purported to work with the DJGPP V2 environment from @@ -193,6 +206,15 @@ The corresponding source is ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh1147s.zip +Mark Elbrecht has sent me notice that bash-2.03 +has become available for DJGPP V2. The files are available as: + +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203b.zip binary +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203d.zip documentation +ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203s.zip source + +Mark has begun to work with bash-2.04. + Ports of bash-1.12 and bash-2.0 are available for OS/2 from ftp://hobbes.nmsu.edu/pub/os2/util/shell/bash_112.zip @@ -201,12 +223,16 @@ ftp://hobbes.nmsu.edu/pub/os2/util/shell/bash-2.0(253).zip I haven't looked at either, but the second appears to be a binary-only distribution. Beware. -6) How can I build bash with gcc? +I have received word that Bash (I'm not sure which version, but I +believe that it's at least bash-2.02.1) is the standard shell on +BeOS. + +A6) How can I build bash with gcc? Bash configures to use gcc by default if it is available. Read the file INSTALL in the distribution for more information. -7) How can I make bash my login shell? +A7) How can I make bash my login shell? Some machines let you use `chsh' to change your login shell. Other systems use `passwd -s' or `passwd -e'. If one of these works for @@ -252,7 +278,34 @@ This will cause login shells to replace themselves with bash running as a login shell. Once you have this working, you can copy your initialization code from ~/.profile to ~/.bash_profile. -8) I just changed my login shell to bash, and now I can't FTP into my +I have received word that the recipe supplied above is insufficient for +machines running CDE. CDE has a maze of twisty little startup files, all +slightly different. + +If you cannot change your login shell in the password file to bash, you +will have to (apparently) live with CDE using the shell in the password +file to run its startup scripts. If you have changed your shell to bash, +there is code in the CDE startup files (on Solaris, at least) to do the +right thing. + +`dtterm' claims to use $SHELL as the default program to start, so if you +can change $SHELL in the CDE startup files, you should be able to use bash +in your terminal windows. + +Setting DTSOURCEPROFILE in ~/.dtprofile will cause the `Xsession' program +to read your login shell's startup files. You may be able to use bash for +the rest of the CDE programs by setting SHELL to bash in ~/.dtprofile as +well, but I have not tried this. + +You can use the above `exec' recipe to start bash when not logging in with +CDE by testing the value of the DT variable: + + if [ -n "$DT" ]; then + [ -f /usr/gnu/bin/bash ] && exec /usr/gnu/bin/bash --login + fi + + +A8) I just changed my login shell to bash, and now I can't FTP into my machine. Why not? You must add the full pathname to bash to the file /etc/shells. As @@ -262,7 +315,7 @@ this before you can make bash your login shell. Most versions of ftpd use this file to prohibit `special' users such as `uucp' and `news' from using FTP. -9) What's the `POSIX 1003.2 standard'? +A9) What's the `POSIX 1003.2 standard'? POSIX is a name originally coined by Richard Stallman for a family of open system standards based on UNIX. There are a @@ -297,7 +350,7 @@ line editing. Only vi-style line editing commands have been standardized; emacs editing commands were left out due to objections. -10) What is the bash `posix mode'? +A10) What is the bash `posix mode'? Although bash is an implementation of the POSIX.2 shell specification, there are areas where the bash default behavior @@ -314,9 +367,97 @@ Reference Manual. Section B: The latest version -11) What's new in version 2.02? - -Bash-2.02 has a number of new features. Here's a short list: +B1) What's new in version 2.05? + +Bash-2.05 contains the following new features (see the manual page for +complete descriptions and the CHANGES and NEWS files in the bash-2.05 +distribution): + +o This version has once again reverted to using locales and strcoll(3) when + processing pattern matching bracket expressions, as POSIX requires. +o Added a new `--init-file' invocation argument as a synonym for `--rcfile', + per the new GNU coding standards. +o The /dev/tcp and /dev/udp redirections now accept service names as well as + port numbers. +o `complete' and `compgen' now take a `-o value' option, which controls some + of the aspects of that compspec. Valid values are: + + default - perform bash default completion if programmable + completion produces no matches + dirnames - perform directory name completion if programmable + completion produces no matches + filenames - tell readline that the compspec produces filenames, + so it can do things like append slashes to + directory names and suppress trailing spaces +o A new loadable builtin, realpath, which canonicalizes and expands symlinks + in pathname arguments. +o When `set' is called without options, it prints function defintions in a + way that allows them to be reused as input. This affects `declare' and + `declare -p' as well. This only happens when the shell is not in POSIX + mode, since POSIX.2 forbids this behavior. + +A short feature history dating from bash-2.0: + +Bash-2.04 introduced the following new features: + +o Programmable word completion with the new `complete' and `compgen' builtins; + examples are provided in examples/complete/complete-examples +o `history' has a new `-d' option to delete a history entry +o `bind' has a new `-x' option to bind key sequences to shell commands +o The prompt expansion code has new `\j' and `\l' escape sequences +o The `no_empty_cmd_completion' shell option, if enabled, inhibits + command completion when TAB is typed on an empty line +o `help' has a new `-s' option to print a usage synopsis +o New arithmetic operators: var++, var--, ++var, --var, expr1,expr2 (comma) +o New ksh93-style arithmetic for command: + for ((expr1 ; expr2; expr3 )); do list; done +o `read' has new options: `-t', `-n', `-d', `-s' +o The redirection code handles several filenames specially: /dev/fd/N, + /dev/stdin, /dev/stdout, /dev/stderr +o The redirection code now recognizes /dev/tcp/HOST/PORT and + /dev/udp/HOST/PORT and tries to open a TCP or UDP socket, respectively, + to the specified port on the specified host +o The ${!prefix*} expansion has been implemented +o A new FUNCNAME variable, which expands to the name of a currently-executing + function +o The GROUPS variable is no longer readonly +o A new shopt `xpg_echo' variable, to control the behavior of echo with + respect to backslash-escape sequences at runtime +o The NON_INTERACTIVE_LOGIN_SHELLS #define has returned + +The version of Readline released with Bash-2.04, Readline-4.1, had several +new features as well: + +o Parentheses matching is always compiled into readline, and controllable + with the new `blink-matching-paren' variable +o The history-search-forward and history-search-backward functions now leave + point at the end of the line when the search string is empty, like + reverse-search-history, and forward-search-history +o A new function for applications: rl_on_new_line_with_prompt() +o New variables for applications: rl_already_prompted, and rl_gnu_readline_p + + +Bash-2.03 had very few new features, in keeping with the convention +that odd-numbered releases provide mainly bug fixes. A number of new +features were added to Readline, mostly at the request of the Cygnus +folks. + +A new shopt option, `restricted_shell', so that startup files can test + whether or not the shell was started in restricted mode +Filename generation is now performed on the words between ( and ) in + compound array assignments (this is really a bug fix) +OLDPWD is now auto-exported, as POSIX.2 requires +ENV and BASH_ENV are read-only variables in a restricted shell +Bash may now be linked against an already-installed Readline library, + as long as the Readline library is version 4 or newer +All shells begun with the `--login' option will source the login shell + startup files, even if the shell is not interactive + +There were lots of changes to the version of the Readline library released +along with Bash-2.03. For a complete list of the changes, read the file +CHANGES in the Bash-2.03 distribution. + +Bash-2.02 contained the following new features: a new version of malloc (based on the old GNU malloc code in previous bash versions) that is more page-oriented, more conservative @@ -382,15 +523,15 @@ grammar tighter and smaller (66 reduce-reduce conflicts gone) lots of code now smaller and faster test suite greatly expanded -12) Are there any user-visible incompatibilities between bash-2.02 and +B2) Are there any user-visible incompatibilities between bash-2.05 and bash-1.14.7? -There are a few incompatibilities between version 1.14.7 and version 2.02. -They are detailed in the file COMPAT in the bash-2.02 distribution. +There are a few incompatibilities between version 1.14.7 and version 2.05. +They are detailed in the file COMPAT in the bash-2.05 distribution. Section C: Differences from other Unix shells -13) How does bash differ from sh, the Bourne shell? +C1) How does bash differ from sh, the Bourne shell? This is a non-comprehensive list of features that differentiate bash from the SVR4.2 shell. The bash manual page explains these more @@ -401,13 +542,15 @@ Things bash has that sh does not: `!' reserved word to invert pipeline return value `time' reserved word to time pipelines and shell builtins the `function' reserved word - the select compound command and reserved word + the `select' compound command and reserved word + arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done new $'...' and $"..." quoting the $(...) form of command substitution the $(, &>, >| prompt string special char translation and variable expansion - auto-export of modified values of variables in initial environment + auto-export of variables in initial environment command search finds functions before builtins bash return builtin will exit a file sourced with `.' builtins: cd -/-L/-P, exec -l/-c/-a, echo -e/-E, hash -p. - export -n/-f/-p/name=value, pwd -L/-P, read -e/-p/-a, + export -n/-f/-p/name=value, pwd -L/-P, + read -e/-p/-a/-t/-n/-d/-s, readonly -a/-f/name=value, trap -l, set +o, set -b/-m/-o option/-h/-p/-B/-C/-H/-P, unset -f/-v, ulimit -m/-p/-u, @@ -443,12 +588,13 @@ Things bash has that sh does not: process substitution aliases and alias/unalias builtins local variables in functions and `local' builtin - readline and command-line editing + readline and command-line editing with programmable completion command history and history/fc builtins csh-like history expansion - other new bash builtins: bind, command, builtin, declare/typeset, - dirs, enable, fc, help, history, logout, - popd, pushd, disown, shopt, printf + other new bash builtins: bind, command, compgen, complete, builtin, + declare/typeset, dirs, enable, fc, help, + history, logout, popd, pushd, disown, shopt, + printf exported functions filename generation when using output redirection (command >a*) POSIX.2-style globbing character classes @@ -459,6 +605,8 @@ Things bash has that sh does not: variable assignments preceding commands affect only that command, even for builtins and functions posix mode + redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr, + /dev/tcp/host/port, /dev/udp/host/port Things sh has that bash does not: uses variable SHACCT to do shell accounting @@ -481,20 +629,23 @@ Implementation differences: bash allows multiple option arguments when invoked (e.g. -x -v); sh allows only a single option argument (`sh -x -v' attempts to open a file named `-v', and, on SunOS 4.1.4, dumps core. - On Solaris 2, sh goes into an infinite loop.) + On Solaris 2.4 and earlier versions, sh goes into an infinite + loop.) sh exits a script if any builtin fails; bash exits only if one of the POSIX.2 `special' builtins fails -14) How does bash differ from the Korn shell, version ksh88? +C2) How does bash differ from the Korn shell, version ksh88? Things bash has or uses that ksh88 does not: long invocation options `!' reserved word + arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done posix mode and posix conformance command hashing tilde expansion for assignment statements that look like $PATH process substitution with named pipes if /dev/fd is not available the ${!param} indirect parameter expansion operator + the ${!param*} prefix expansion operator the ${param:length[:offset]} parameter substring operator the ${param/pat[/string]} parameter pattern substitution operator variables: BASH, BASH_VERSION, BASH_VERSINFO, UID, EUID, SHLVL, @@ -502,18 +653,19 @@ Things bash has or uses that ksh88 does not: HISTFILESIZE, HISTIGNORE, HISTCONTROL, PROMPT_COMMAND, IGNOREEOF, FIGNORE, INPUTRC, HOSTFILE, DIRSTACK, PIPESTATUS, HOSTNAME, OPTERR, SHELLOPTS, GLOBIGNORE, - GROUPS, histchars, auto_resume + GROUPS, FUNCNAME, histchars, auto_resume prompt expansion with backslash escapes and command substitution redirection: &> (stdout and stderr) - more extensive and extensible editing and completion + more extensive and extensible editing and programmable completion builtins: bind, builtin, command, declare, dirs, echo -e/-E, enable, exec -l/-c/-a, fc -s, export -n/-f/-p, hash, help, history, jobs -x/-r/-s, kill -s/-n/-l, local, logout, popd, pushd, - read -e/-p/-a, readonly -a/-n/-f/-p, set -o braceexpand/ - -o histexpand/-o interactive-comments/-o notify/-o physical/ - -o posix/-o hashall/-o onecmd/-h/-B/-C/-b/-H/-P, set +o, - suspend, trap -l, type, typeset -a/-F/-p, ulimit -u, - umask -S, alias -p, shopt, disown, printf + read -e/-p/-a/-t/-n/-d/-s, readonly -a/-n/-f/-p, + set -o braceexpand/-o histexpand/-o interactive-comments/ + -o notify/-o physical/-o posix/-o hashall/-o onecmd/ + -h/-B/-C/-b/-H/-P, set +o, suspend, trap -l, type, + typeset -a/-F/-p, ulimit -u, umask -S, alias -p, shopt, + disown, printf, complete, compgen `!' csh-style history expansion POSIX.2-style globbing character classes POSIX.2-style globbing equivalence classes @@ -521,10 +673,12 @@ Things bash has or uses that ksh88 does not: egrep-like extended pattern matching operators case-insensitive pattern matching and globbing `**' arithmetic operator to do exponentiation + redirection to /dev/fd/N, /dev/stdin, /dev/stdout, /dev/stderr Things ksh88 has or uses that bash does not: tracked aliases - variables: ERRNO, FPATH, COLUMNS, LINES, EDITOR, VISUAL + variables: ERRNO, FPATH, EDITOR, VISUAL + trap on ERR co-processes (|&, >&p, <&p) weirdly-scoped functions typeset +f to list all function names without definitions @@ -541,32 +695,31 @@ Implementation differences: bash has exported functions bash command search finds functions before builtins -15) Which new features in ksh-93 are not in bash, and which are? +C3) Which new features in ksh-93 are not in bash, and which are? -New things in ksh-93 not in bash-2.02: +New things in ksh-93 not in bash-2.05: associative arrays floating point arithmetic - ++, --, comma arithmetic operators math library functions ${!name[sub]} name of subscript for associative array - ${!prefix*} and {!prefix@} variable name prefix expansions `.' is allowed in variable names to create a hierarchical namespace more extensive compound assignment syntax discipline functions `sleep' and `getconf' builtins (bash has loadable versions) typeset -n and `nameref' variables KEYBD trap - variables: .sh.edchar, .sh.edmode, .sh.edcol, .sh.edtext, HISTEDIT, - .sh.version, .sh.name, .sh.subscript, .sh.value + variables: .sh.edchar, .sh.edmode, .sh.edcol, .sh.edtext, .sh.version, + .sh.name, .sh.subscript, .sh.value, HISTEDIT backreferences in pattern matching - print -f (bash has a loadable version of print and the printf builtin) + print -f (bash uses printf) `fc' has been renamed to `hist' - read -t/-d `.' can execute shell functions -New things in ksh-93 present in bash-2.02: - ?: arithmetic operator - expansions: ${!param}, ${param:offset[:len]}, ${param/pat[/str]} +New things in ksh-93 present in bash-2.04: + for (( expr1; expr2; expr3 )) ; do list; done - arithmetic for command + ?:, ++, --, `expr1 , expr2' arithmetic operators + expansions: ${!param}, ${param:offset[:len]}, ${param/pat[/str]}, + ${!param*} compound array assignment the `!' reserved word loadable builtins -- but ksh uses `builtin' while bash uses `enable' @@ -576,6 +729,7 @@ New things in ksh-93 present in bash-2.02: set -o notify/-C changes to kill builtin read -A (bash uses read -a) + read -t/-d trap -p exec -c/-a `.' restores the positional parameters when it completes @@ -588,16 +742,37 @@ New things in ksh-93 present in bash-2.02: Section D: Why does bash do some things differently than other Unix shells? -16) Why does bash run a different version of `command' than +D1) Why does bash run a different version of `command' than `which command' says it will? -`which' is actually a csh script that assumes you're running csh. -It reads the csh startup files from your home directory and uses -those to determine which `command' will be invoked. Since bash -doesn't use any of those startup files, there's a good chance -that your bash environment differs from your csh environment. +On many systems, `which' is actually a csh script that assumes +you're running csh. In tcsh, `which' and its cousin `where' +are builtins. On other Unix systems, `which' is a perl script +that uses the PATH environment variable. + +The csh script version reads the csh startup files from your +home directory and uses those to determine which `command' will +be invoked. Since bash doesn't use any of those startup files, +there's a good chance that your bash environment differs from +your csh environment. The bash `type' builtin does everything +`which' does, and will report correct results for the running +shell. If you're really wedded to the name `which', try adding +the following function definition to your .bashrc: + + which() + { + builtin type "$@" + } + +If you're moving from tcsh and would like to bring `where' along +as well, use this function: -17) Why doesn't bash treat brace expansions exactly like csh? + where() + { + builtin type -a "$@" + } + +D2) Why doesn't bash treat brace expansions exactly like csh? The only difference between bash and csh brace expansion is that bash requires a brace expression to contain at least one unquoted @@ -608,7 +783,7 @@ compatibility. Bash, ksh, zsh, and pd-ksh all implement brace expansion this way. -18) Why doesn't bash have csh variable modifiers? +D3) Why doesn't bash have csh variable modifiers? Posix has specified a more powerful, albeit somewhat more cryptic, mechanism cribbed from ksh, and bash implements it. @@ -663,20 +838,20 @@ Given $b:e ${b##*.} xxx -19) How can I make my csh aliases work when I convert to bash? +D4) How can I make my csh aliases work when I convert to bash? Bash uses a different syntax to support aliases than csh does. The details can be found in the documentation. We have provided a shell script which does most of the work of conversion for you; -this script can be found in ./examples/misc/alias-conv.sh. Here is +this script can be found in ./examples/misc/aliasconv.sh. Here is how you use it: Start csh in the normal way for you. (e.g., `csh') -Pipe the output of `alias' through `alias-conv.sh', saving the +Pipe the output of `alias' through `aliasconv.sh', saving the results into `bash_aliases': - alias | alias-conv.sh >bash_aliases + alias | bash aliasconv.sh >bash_aliases Edit `bash_aliases', carefully reading through any created functions. You will need to change the names of some csh specific @@ -706,7 +881,7 @@ simply `cshtobash' to convert your normal interactive environment, or as `cshtobash ~/.login' to convert your login environment. -20) How can I pipe standard output and standard error from one command to +D5) How can I pipe standard output and standard error from one command to another, like csh does with `|&'? Use @@ -716,11 +891,11 @@ The key is to remember that piping is performed before redirection, so file descriptor 1 points to the pipe when it is duplicated onto file descriptor 2. -21) Now that I've converted from ksh to bash, are there equivalents to +D6) Now that I've converted from ksh to bash, are there equivalents to ksh features like autoloaded functions and the `whence' command? -There are features in ksh-88 that do not have direct bash equivalents. -Most, however, can be emulated with very little trouble. +There are features in ksh-88 and ksh-93 that do not have direct bash +equivalents. Most, however, can be emulated with very little trouble. ksh-88 feature Bash equivalent -------------- --------------- @@ -732,10 +907,18 @@ cd, print, whence function substitutes in examples/functions/kshenv autoloaded functions examples/functions/autoload is the same as typeset -fu read var?prompt read -p prompt var +ksh-93 feature Bash equivalent +-------------- --------------- +sleep, getconf Bash has loadable versions in examples/loadables +${.sh.version} $BASH_VERSION +print -f printf +hist alias fc=hist +$HISTEDIT $FCEDIT + Section E: How can I get bash to do certain things, and why does bash do things the way it does? -22) Why is the bash builtin `test' slightly different from /bin/test? +E1) Why is the bash builtin `test' slightly different from /bin/test? The specific example used here is [ ! x -o x ], which is false. @@ -764,7 +947,7 @@ of the 3 Arg case. As you can see, the test becomes (not (x or x)), which is false. -23) Why does bash sometimes say `Broken pipe'? +E2) Why does bash sometimes say `Broken pipe'? If a sequence of commands appears in a pipeline, and one of the reading commands finishes before the writer has finished, the @@ -779,62 +962,11 @@ will try to write on a pipe without a reader. In that case, bash will print `Broken pipe' to stderr when ps is killed by a SIGPIPE. -24) How can I get bash to read and display eight-bit characters? - -This is a process requiring several steps. - -First, you must ensure that the `physical' data path is a full eight -bits. For xterms, for example, the `vt100' resources `eightBitInput' -and `eightBitOutput' should be set to `true'. - -Once you have set up an eight-bit path, you must tell the kernel and -tty driver to leave the eighth bit of characters alone when processing -keyboard input. Use `stty' to do this: - - stty cs8 -istrip -parenb - -For old BSD-style systems, you can use - - stty pass8 - -You may also need - - stty even odd - -Finally, you need to tell readline that you will be inputting and -displaying eight-bit characters. You use readline variables to do -this. These variables can be set in your .inputrc or using the bash -`bind' builtin. Here's an example using `bind': - - bash$ bind 'set convert-meta off' - bash$ bind 'set meta-flag on' - bash$ bind 'set output-meta on' - -The `set' commands between the single quotes may also be placed -in ~/.inputrc. +You can build a version of bash that will not report SIGPIPE errors +by uncommenting the definition of DONT_REPORT_SIGPIPE in the file +config-top.h. -25) How do I write a function `x' to replace builtin command `x', but - still invoke the command from within the function? - -This is why the `command' and `builtin' builtins exist. The -`command' builtin executes the command supplied as its first -argument, skipping over any function defined with that name. The -`builtin' builtin executes the builtin command given as its first -argument directly. - -For example, to write a function to replace `cd' that writes the -hostname and current directory to an xterm title bar, use -something like the following: - - cd() - { - builtin cd "$@" && xtitle "$HOST: $PWD" - } - -This could also be written using `command' instead of `builtin'; -the version above is marginally more efficient. - -26) When I have terminal escape sequences in my prompt, why does bash +E3) When I have terminal escape sequences in my prompt, why does bash wrap lines at the wrong column? Readline, the line editing library that bash uses, does not know @@ -850,42 +982,14 @@ characters in the prompt strings take up no screen space. Use the \[ escape to begin a sequence of non-printing characters, and the \] escape to signal the end of such a sequence. -27) How can I find the value of a shell variable whose name is the value - of another shell variable? - -Bash-2.02 supports this directly. You can use - - ${!var} - -For example, the following sequence of commands will echo `z': - - var1=var2 - var2=z - echo ${!var1} - -For sh compatibility, use the `eval' builtin. The important -thing to remember is that `eval' expands the arguments you give -it again, so you need to quote the parts of the arguments that -you want `eval' to act on. - -For example, this expression prints the value of the last positional -parameter: - - eval echo \"\$\{$#\}\" - -The expansion of the quoted portions of this expression will be -deferred until `eval' runs, while the `$#' will be expanded -before `eval' is executed. In bash-2.02, - - echo ${!#} - -does the same thing. - -28) If I pipe the output of a command into `read variable', why doesn't +E4) If I pipe the output of a command into `read variable', why doesn't the output show up in $variable when the read command finishes? This has to do with the parent-child relationship between Unix -processes. +processes. It affects all commands run in pipelines, not just +simple calls to `read'. For example, piping a command's output +into a `while' loop that repeatedly calls `read' will result in +the same behavior. Each element of a pipeline runs in a separate process, a child of the shell running the pipeline. A subprocess cannot affect its @@ -937,13 +1041,13 @@ this. This is the general approach -- in most cases you will not need to set $IFS to a different value. -29) I have a bunch of shell scripts that use backslash-escaped characters +E5) I have a bunch of shell scripts that use backslash-escaped characters in arguments to `echo'. Bash doesn't interpret these characters. Why not, and how can I make it understand them? This is the behavior of echo on most Unix System V machines. -The bash builtin `echo' is modelled after the 9th Edition +The bash builtin `echo' is modeled after the 9th Edition Research Unix version of `echo'. It does not interpret backslash-escaped characters in its argument strings by default; it requires the use of the -e option to enable the @@ -957,7 +1061,11 @@ configure with the --enable-usg-echo-default option to turn this on. Be aware that this will cause some of the tests run when you type `make tests' to fail. -30) Why doesn't a while or for loop get suspended when I type ^Z? +There is a shell option, `xpg_echo', settable with `shopt' that will +change the behavior of echo at runtime. Enabling this option turns +on expansion of backslash-escape sequences. + +E6) Why doesn't a while or for loop get suspended when I type ^Z? This is a consequence of how job control works on Unix. The only thing that can be suspended is the process group. This is a single @@ -972,41 +1080,103 @@ If you want to be able to stop the entire loop, you need to put it within parentheses, which will force the loop into a subshell that may be stopped (and subsequently restarted) as a single unit. -31) How can I make the bash `time' reserved word print timing output that - looks like the output from my system's /usr/bin/time? +E7) What about empty for loops in Makefiles? -The bash command timing code looks for a variable `TIMEFORMAT' and -uses its value as a format string to decide how to display the -timing statistics. +It's fairly common to see constructs like this in automatically-generated +Makefiles: -The value of TIMEFORMAT is a string with `%' escapes expanded in a -fashion similar in spirit to printf(3). The manual page explains -the meanings of the escape sequences in the format string. +SUBDIRS = @SUBDIRS@ -If TIMEFORMAT is not set, bash acts as if the following assignment had -been performed: + ... - TIMEFORMAT=$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS' +subdirs-clean: + for d in ${SUBDIRS}; do \ + ( cd $$d && ${MAKE} ${MFLAGS} clean ) \ + done -The POSIX.2 default time format (used by `time -p command') is +When SUBDIRS is empty, this results in a command like this being passed to +bash: - TIMEFORMAT=$'real %2R\nuser %2U\nsys %2S' + for d in ; do + ( cd $d && ${MAKE} ${MFLAGS} clean ) + done -The BSD /usr/bin/time format can be emulated with: +This is a syntax error. If the reserved word `in' is present, a word must +follow it before the semicolon or newline. The language in the manual page +referring to the list of words being empty refers to the list after it is +expanded. There must be at least one word following the `in' when the +construct is parsed. - TIMEFORMAT=$'\t%1R real\t%1U user\t%1S sys' +The idiomatic Makefile solution is something like: -The System V /usr/bin/time format can be emulated with: +SUBDIRS = @SUBDIRS@ - TIMEFORMAT=$'\nreal\t%1R\nuser\t%1U\nsys\t%1S' +subdirs-clean: + subdirs=$SUBDIRS ; for d in $$subdirs; do \ + ( cd $$d && ${MAKE} ${MFLAGS} clean ) \ + done -The ksh format can be emulated with: - TIMEFORMAT=$'\nreal\t%2lR\nuser\t%2lU\nsys\t%2lS' +The POSIX.2 interpretation committee has considered this issue and declared +that the bash implemenation is correct, according to the standard: + +http://www.pasc.org/interps/unofficial/db/p1003.2/pasc-1003.2-169.html + +E8) Why does the arithmetic evaluation code complain about `08'? + +The bash arithmetic evaluation code (used for `let', $(()), (()), and in +other places), interprets a leading `0' in numeric constants as denoting +an octal number, and a leading `0x' as denoting hexadecimal. This is +in accordance with the POSIX.2 spec, section 2.9.2.1, which states that +arithmetic constants should be handled as signed long integers as defined +by the ANSI/ISO C standard. + +The POSIX.2 interpretation committee has confirmed this: + +http://www.pasc.org/interps/unofficial/db/p1003.2/pasc-1003.2-173.html + +E9) Why does the pattern matching expression [A-Z]* match files beginning + with every letter except `z'? + +Bash-2.05 and later versions have reverted to the bash-2.03 behavior of +honoring the current locale setting when processing ranges within pattern +matching bracket expressions ([A-Z]). This is what POSIX.2 and SUSv2/XPG5 +specify. + +The behavior of the matcher in bash-2.05 depends on the current LC_COLLATE +setting. Setting this variable to `C' or `POSIX' will result in the +traditional behavior ([A-Z] matches all uppercase ASCII characters). +Many other locales, including the en_US locale (the default on many US +versions of Linux) collate the upper and lower case letters like this: + + AaBb...Zz + +which means that [A-Z] matches every letter except `z'. + +The portable way to specify upper case letters is [:upper:] instead of +A-Z; lower case may be specified as [:lower:] instead of a-z. + +Look at the manual pages for setlocale(3), strcoll(3), and, if it is +present, locale(1). If you have locale(1), you can use it to find +your current locale information even if you do not have any of the +LC_ variables set. + +My advice is to put + + export LC_COLLATE=C + +into /etc/profile and inspect any shell scripts run from cron for +constructs like [A-Z]. This will prevent things like + + rm [A-Z]* + +from removing every file in the current directory except those beginning +with `z' and still allow individual users to change the collation order. +Users may put the above command into their own profiles as well, of course. Section F: Things to watch out for on certain Unix versions -32) Why can't I use command line editing in my `cmdtool'? +F1) Why can't I use command line editing in my `cmdtool'? The problem is `cmdtool' and bash fighting over the input. When scrolling is enabled in a cmdtool window, cmdtool puts the tty in @@ -1034,7 +1204,7 @@ The bash command-line editing should behave better in the new cmdtool. If this works, you can put the assignment to TERMCAP in your bashrc file. -33) I built bash on Solaris 2. Why do globbing expansions and filename +F2) I built bash on Solaris 2. Why do globbing expansions and filename completion chop off the first few characters of each filename? This is the consequence of building bash on SunOS 5 and linking @@ -1054,7 +1224,7 @@ If you have installed the Sun C compiler, you may also need to put /usr/ccs/bin and /opt/SUNWspro/bin into your $PATH before /usr/ucb. -34) Why does bash dump core after I interrupt username completion or +F3) Why does bash dump core after I interrupt username completion or `~user' tilde expansion on a machine running NIS? This is a famous and long-standing bug in the SunOS YP (sorry, NIS) @@ -1077,7 +1247,7 @@ times; that's probably why this has never been fixed. You can run configure with the `--without-gnu-malloc' option to use the C library malloc and avoid the problem. -35) I'm running SVR4.2. Why is the line erased every time I type `@'? +F4) I'm running SVR4.2. Why is the line erased every time I type `@'? The `@' character is the default `line kill' character in most versions of System V, including SVR4.2. You can change this @@ -1088,7 +1258,7 @@ change the line kill character to control-u, type where the `^' and `U' can be two separate characters. -36) Why does bash report syntax errors when my C News scripts use a +F5) Why does bash report syntax errors when my C News scripts use a redirection before a subshell command? The actual command in question is something like @@ -1100,16 +1270,211 @@ is, in fact, a syntax error. Redirections may only precede `simple commands'. A subshell construct such as the above is one of the shell's `compound commands'. A redirection may only follow a compound command. -The file CWRU/sh-redir-hack in the bash-2.02 distribution is an +This affects the mechanical transformation of commands that use `cat' +to pipe a file into a command (a favorite Useless-Use-Of-Cat topic on +comp.unix.shell). While most commands of the form + + cat file | command + +can be converted to `< file command', shell control structures such as +loops and subshells require `command < file'. + +The file CWRU/sh-redir-hack in the bash-2.05 distribution is an (unofficial) patch to parse.y that will modify the grammar to support this construct. It will not apply with `patch'; you must modify parse.y by hand. Note that if you apply this, you must recompile with -DREDIRECTION_HACK. This introduces a large number of reduce/reduce conflicts into the shell grammar. -Section G: Where do I go from here? +F6) Why can't I use vi-mode editing on Red Hat Linux 6.1? + +The short answer is that Red Hat screwed up. + +The long answer is that they shipped an /etc/inputrc that only works +for emacs mode editing, and then screwed all the vi users by setting +INPUTRC to /etc/inputrc in /etc/profile. + +The short fix is to do one of the following: remove or rename +/etc/inputrc, set INPUTRC=~/.inputrc in ~/.bashrc (or .bash_profile, +but make sure you export it if you do), remove the assignment to +INPUTRC from /etc/profile, add + + set keymap emacs + +to the beginning of /etc/inputrc, or bracket the key bindings in +/etc/inputrc with these lines + + $if mode=emacs + [...] + $endif + +Section G: How can I get bash to do certain common things? + +G1) How can I get bash to read and display eight-bit characters? + +This is a process requiring several steps. + +First, you must ensure that the `physical' data path is a full eight +bits. For xterms, for example, the `vt100' resources `eightBitInput' +and `eightBitOutput' should be set to `true'. + +Once you have set up an eight-bit path, you must tell the kernel and +tty driver to leave the eighth bit of characters alone when processing +keyboard input. Use `stty' to do this: + + stty cs8 -istrip -parenb + +For old BSD-style systems, you can use + + stty pass8 + +You may also need + + stty even odd + +Finally, you need to tell readline that you will be inputting and +displaying eight-bit characters. You use readline variables to do +this. These variables can be set in your .inputrc or using the bash +`bind' builtin. Here's an example using `bind': + + bash$ bind 'set convert-meta off' + bash$ bind 'set meta-flag on' + bash$ bind 'set output-meta on' + +The `set' commands between the single quotes may also be placed +in ~/.inputrc. + +G2) How do I write a function `x' to replace builtin command `x', but + still invoke the command from within the function? + +This is why the `command' and `builtin' builtins exist. The +`command' builtin executes the command supplied as its first +argument, skipping over any function defined with that name. The +`builtin' builtin executes the builtin command given as its first +argument directly. + +For example, to write a function to replace `cd' that writes the +hostname and current directory to an xterm title bar, use +something like the following: + + cd() + { + builtin cd "$@" && xtitle "$HOST: $PWD" + } + +This could also be written using `command' instead of `builtin'; +the version above is marginally more efficient. + +G3) How can I find the value of a shell variable whose name is the value + of another shell variable? + +Versions of Bash newer than Bash-2.0 support this directly. You can use + + ${!var} + +For example, the following sequence of commands will echo `z': + + var1=var2 + var2=z + echo ${!var1} + +For sh compatibility, use the `eval' builtin. The important +thing to remember is that `eval' expands the arguments you give +it again, so you need to quote the parts of the arguments that +you want `eval' to act on. + +For example, this expression prints the value of the last positional +parameter: + + eval echo \"\$\{$#\}\" + +The expansion of the quoted portions of this expression will be +deferred until `eval' runs, while the `$#' will be expanded +before `eval' is executed. In versions of bash later than bash-2.0, + + echo ${!#} + +does the same thing. + +G4) How can I make the bash `time' reserved word print timing output that + looks like the output from my system's /usr/bin/time? + +The bash command timing code looks for a variable `TIMEFORMAT' and +uses its value as a format string to decide how to display the +timing statistics. + +The value of TIMEFORMAT is a string with `%' escapes expanded in a +fashion similar in spirit to printf(3). The manual page explains +the meanings of the escape sequences in the format string. + +If TIMEFORMAT is not set, bash acts as if the following assignment had +been performed: + + TIMEFORMAT=$'\nreal\t%3lR\nuser\t%3lU\nsys\t%3lS' + +The POSIX.2 default time format (used by `time -p command') is + + TIMEFORMAT=$'real %2R\nuser %2U\nsys %2S' + +The BSD /usr/bin/time format can be emulated with: + + TIMEFORMAT=$'\t%1R real\t%1U user\t%1S sys' + +The System V /usr/bin/time format can be emulated with: + + TIMEFORMAT=$'\nreal\t%1R\nuser\t%1U\nsys\t%1S' + +The ksh format can be emulated with: + + TIMEFORMAT=$'\nreal\t%2lR\nuser\t%2lU\nsys\t%2lS' + +G5) How do I get the current directory into my prompt? + +Bash provides a number of backslash-escape sequences which are expanded +when the prompt string (PS1 or PS2) is displayed. The full list is in +the manual page. + +The \w expansion gives the full pathname of the current directory, with +a tilde (`~') substituted for the current value of $HOME. The \W +expansion gives the basename of the current directory. To put the full +pathname of the current directory into the path without any tilde +subsitution, use $PWD. Here are some examples: + + PS1='\w$ ' # current directory with tilde + PS1='\W$ ' # basename of current directory + PS1='$PWD$ ' # full pathname of current directory + +The single quotes are important in the final example to prevent $PWD from +being expanded when the assignment to PS1 is performed. + +G6) How can I rename "*.foo" to "*.bar"? + +Use the pattern removal functionality described in D3. The following `for' +loop will do the trick: + + for f in *.foo; do + mv $f ${f%foo}bar + done + +G7) How can I translate a filename from uppercase to lowercase? + +The script examples/functions/lowercase, originally written by John DuBois, +will do the trick. The converse is left as an exercise. + +G8) How can I write a filename expansion (globbing) pattern that will match + all files in the current directory except "." and ".."? + +You must have set the `extglob' shell option using `shopt -s extglob' to use +this: + + echo .!(.|) * + +A solution that works without extended globbing is given in the Unix Shell +FAQ, posted periodically to comp.unix.shell. + +Section H: Where do I go from here? -37) How do I report bugs in bash, and where should I look for fixes and +H1) How do I report bugs in bash, and where should I look for fixes and advice? Use the `bashbug' script to report bugs. It is built and @@ -1117,7 +1482,7 @@ installed at the same time as bash. It provides a standard template for reporting a problem and automatically includes information about your configuration and build environment. -`bashbug' sends its reports to bug-bash@prep.ai.mit.edu, which +`bashbug' sends its reports to bug-bash@gnu.org, which is a large mailing list gatewayed to the usenet newsgroup gnu.bash.bug. Bug fixes, answers to questions, and announcements of new releases @@ -1125,24 +1490,23 @@ are all posted to gnu.bash.bug. Discussions concerning bash features and problems also take place there. To reach the bash maintainers directly, send mail to -bash-maintainers@prep.ai.mit.edu. +bash-maintainers@gnu.org. -38) What kind of bash documentation is there? +H2) What kind of bash documentation is there? First, look in the doc directory in the bash distribution. It should contain at least the following files: bash.1 an extensive, thorough Unix-style manual page builtins.1 a manual page covering just bash builtin commands -bashref.texi a reference manual in GNU info format -bash.html an HTML version of the manual page -bashref.html an HTML version of the reference manual +bashref.texi a reference manual in GNU tex`info format +bashref.info an info version of the reference manual FAQ this file article.ms text of an article written for The Linux Journal readline.3 a man page describing readline -Postscript files created from the above source are available in -the documentation distribution. +Postscript, HTML, and ASCII files created from the above source are +available in the documentation distribution. There is additional documentation available for anonymous FTP from host ftp.cwru.edu in the `pub/bash' directory. @@ -1158,33 +1522,37 @@ A second edition of this book is available, published in January, 1998. The ISBN number is 1-56592-347-2. Look for it in the same fine bookstores or on the web. -39) What's coming in future versions? +H3) What's coming in future versions? These are features I plan to include in a future version of bash. -a bash debugger (a minimally-tested version is included with bash-2.02) -Programmable completion a la zsh +a bash debugger (a minimally-tested version is included with bash-2.05) +associative arrays +changes to the DEBUG trap to be compatible with ksh93 (which runs the +trap before each simple command, instead of after each one like previous +versions) +an implementation of the ksh-like ERR trap -40) What's on the bash `wish list' for future versions? +H4) What's on the bash `wish list' for future versions? These are features that may or may not appear in a future version of bash. -associative arrays (not really all that hard) breaking some of the shell functionality into embeddable libraries +a module system like zsh's, using dynamic loading like builtins better internationalization using GNU `gettext' an option to use external files for the long `help' text -timeouts for the `read' builtin -the ksh-93 ${!prefix*} and ${!prefix@} operators -arithmetic ++ and -- prefix and postfix operators date-stamped command history +a bash programmer's guide with a chapter on creating loadable builtins +a better loadable interface to perl with access to the shell builtins and + variables (contributions gratefully accepted) -41) When will the next release appear? +H5) When will the next release appear? -The next version will appear sometime in 1998. Never make +The next version will appear sometime in 2001 or 2002. Never make predictions. -This document is Copyright 1995, 1996, 1998 by Chester Ramey. +This document is Copyright 1995-2001 by Chester Ramey. Permission is hereby granted, without written agreement and without license or royalty fees, to use, copy, and distribute