Imported from ../bash-2.04.tar.gz.
This commit is contained in:
Jari Aalto
parent
b72432fdcc
commit
bb70624e96
387 changed files with 28522 additions and 9334 deletions
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doc/FAQ
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doc/FAQ
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@ -1,4 +1,4 @@
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This is the Bash FAQ, version 3.0, for Bash version 2.03.
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This is the Bash FAQ, version 3.7, for Bash version 2.04.
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This document contains a set of frequently-asked questions concerning
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Bash, the GNU Bourne-Again Shell. Bash is a freely-available command
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@ -15,6 +15,8 @@ This document is available for anonymous FTP with the URL
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ftp://ftp.cwru.edu/pub/bash/FAQ
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The Bash home page is http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html
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----------
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Contents:
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@ -34,8 +36,8 @@ A10) What is the bash `posix mode'?
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Section B: The latest version
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B1) What's new in version 2.03?
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B2) Are there any user-visible incompatibilities between bash-2.03 and
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B1) What's new in version 2.04?
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B2) Are there any user-visible incompatibilities between bash-2.04 and
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bash-1.14.7?
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Section C: Differences from other Unix shells
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@ -56,26 +58,18 @@ D5) How can I pipe standard output and standard error from one command to
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D6) Now that I've converted from ksh to bash, are there equivalents to
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ksh features like autoloaded functions and the `whence' command?
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Section E: How can I get bash to do certain things, and why does bash do
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things the way it does?
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Section E: Why does bash do certain things the way it does?
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E1) Why is the bash builtin `test' slightly different from /bin/test?
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E2) Why does bash sometimes say `Broken pipe'?
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E3) How can I get bash to read and display eight-bit characters?
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E4) How do I write a function `x' to replace builtin command `x', but
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still invoke the command from within the function?
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E5) When I have terminal escape sequences in my prompt, why does bash
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E3) When I have terminal escape sequences in my prompt, why does bash
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wrap lines at the wrong column?
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E6) How can I find the value of a shell variable whose name is the value
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of another shell variable?
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E7) If I pipe the output of a command into `read variable', why doesn't
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E4) If I pipe the output of a command into `read variable', why doesn't
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the output show up in $variable when the read command finishes?
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E8) I have a bunch of shell scripts that use backslash-escaped characters
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E5) I have a bunch of shell scripts that use backslash-escaped characters
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in arguments to `echo'. Bash doesn't interpret these characters. Why
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not, and how can I make it understand them?
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E9) Why doesn't a while or for loop get suspended when I type ^Z?
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E10) How can I make the bash `time' reserved word print timing output that
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looks like the output from my system's /usr/bin/time?
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E6) Why doesn't a while or for loop get suspended when I type ^Z?
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Section F: Things to watch out for on certain Unix versions
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@ -87,15 +81,31 @@ F3) Why does bash dump core after I interrupt username completion or
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F4) I'm running SVR4.2. Why is the line erased every time I type `@'?
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F5) Why does bash report syntax errors when my C News scripts use a
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redirection before a subshell command?
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F6) Why can't I use vi-mode editing on Red Hat Linux 6.1?
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Section G: Where do I go from here?
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Section G: How can I get bash to do certain common things?
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G1) How do I report bugs in bash, and where should I look for fixes and
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G1) How can I get bash to read and display eight-bit characters?
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G2) How do I write a function `x' to replace builtin command `x', but
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still invoke the command from within the function?
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G3) How can I find the value of a shell variable whose name is the value
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of another shell variable?
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G4) How can I make the bash `time' reserved word print timing output that
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looks like the output from my system's /usr/bin/time?
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G5) How do I get the current directory into my prompt?
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G6) How can I rename "*.foo" to "*.bar"?
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G7) How can I translate a filename from uppercase to lowercase?
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G8) How can I write a filename expansion (globbing) pattern that will match
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all files in the current directory except "." and ".."?
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Section H: Where do I go from here?
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H1) How do I report bugs in bash, and where should I look for fixes and
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advice?
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G2) What kind of bash documentation is there?
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G3) What's coming in future versions?
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G4) What's on the bash `wish list'?
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G5) When will the next release appear?
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H2) What kind of bash documentation is there?
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H3) What's coming in future versions?
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H4) What's on the bash `wish list'?
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H5) When will the next release appear?
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----------
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Section A: The Basics
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@ -120,22 +130,22 @@ of Case Western Reserve University.
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A2) What's the latest version?
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The latest version is 2.03, first made available on Friday, 19 Feburary 1999.
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The latest version is 2.04, first made available on Friday, 17 March 2000.
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A3) Where can I get it?
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Bash is the GNU project's shell, and so is available from the
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master GNU archive site, ftp.gnu.org, and its mirrors. The
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latest version is also available for FTP from ftp.cwru.edu.
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The following URLs tell how to get version 2.03:
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The following URLs tell how to get version 2.04:
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ftp://ftp.gnu.org/pub/gnu/bash-2.03.tar.gz
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ftp://ftp.cwru.edu/pub/bash/bash-2.03.tar.gz
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ftp://ftp.gnu.org/pub/gnu/bash/bash-2.04.tar.gz
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ftp://ftp.cwru.edu/pub/bash/bash-2.04.tar.gz
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Formatted versions of the documentation are available with the URLs:
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ftp://ftp.gnu.org/pub/gnu/bash-doc-2.03.tar.gz
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ftp://ftp.cwru.edu/pub/bash/bash-doc-2.03.tar.gz
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ftp://ftp.gnu.org/pub/gnu/bash/bash-doc-2.04.tar.gz
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ftp://ftp.cwru.edu/pub/bash/bash-doc-2.04.tar.gz
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A4) On what machines will bash run?
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@ -150,25 +160,25 @@ More information appears in the file `INSTALL' in the distribution.
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A5) Will bash run on operating systems other than Unix?
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Configuration specifics for Unix-like systems such as QNX and
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LynxOS are included in the distribution. Bash-2.03 should
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LynxOS are included in the distribution. Bash-2.04 should
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compile and run on Minix 2.0 (patches were contributed), but I
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don't believe anyone has built bash-2.x on earlier Minix versions
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yet.
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Bash has been ported to versions of Windows implementing the Win32
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programming interface. This includes Windows 95 and Windows NT.
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The port was done by Cygnus Solutions as part of their GNU-Win32
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The port was done by Cygnus Solutions as part of their CYGWIN
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project. For more information about the project, look at the URL
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http://www.cygnus.com/misc/gnu-win32
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http:/sourceware.cygnus.com/cygwin
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Cygnus originally ported bash-1.14.7, and that port was part of their
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early GNU-Win32 releases. Cygnus has also done a port of bash-2.01 to the
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GNU-Win32 environment, and it is available as part of their current
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release. (They may have upgraded by now.)
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early GNU-Win32 (the original name) releases. Cygnus has also done a
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port of bash-2.02.1 to the CYGWIN environment, and it is available as
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part of their current release. (They may have upgraded by now.)
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Bash-2.03 should require no local Cygnus changes to build and run under
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GNU-WIN32.
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Bash-2.04 should require no local Cygnus changes to build and run under
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CYGWIN.
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The Cygnus port works only on Intel machines. There is a port of bash
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(I don't know which version) to the alpha/NT environment available from
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@ -185,7 +195,7 @@ but Interix users should fetch
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ftp://ftp.interix.com/pub/tw/unsup/bash.diffs.tar.gz
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and read the README.OpenNT file in that archive. It will detail the
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arguments configure needs to build on Interix. A configure cache
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arguments `configure' needs to build on Interix. A configure cache
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file for Interix is in the bash distribution in cross-build/opennt.cache;
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copy that to `config.cache' before starting configure.
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@ -203,6 +213,15 @@ The corresponding source is
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ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh1147s.zip
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Mark Elbrecht <snowball3@bigfoot.com> has sent me notice that bash-2.03
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has become available for DJGPP V2. The files are available as:
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ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203b.zip binary
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ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203d.zip documentation
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ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh203s.zip source
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Mark has begun to work with bash-2.04.
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Ports of bash-1.12 and bash-2.0 are available for OS/2 from
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ftp://hobbes.nmsu.edu/pub/os2/util/shell/bash_112.zip
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@ -211,6 +230,10 @@ ftp://hobbes.nmsu.edu/pub/os2/util/shell/bash-2.0(253).zip
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I haven't looked at either, but the second appears to be a binary-only
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distribution. Beware.
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I have received word that Bash (I'm not sure which version, but I
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believe that it's at least bash-2.02.1) is the standard shell on
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BeOS.
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A6) How can I build bash with gcc?
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Bash configures to use gcc by default if it is available. Read the
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@ -262,6 +285,33 @@ This will cause login shells to replace themselves with bash running as
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a login shell. Once you have this working, you can copy your initialization
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code from ~/.profile to ~/.bash_profile.
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I have received word that the recipe supplied above is insufficient for
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machines running CDE. CDE has a maze of twisty little startup files, all
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slightly different.
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If you cannot change your login shell in the password file to bash, you
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will have to (apparently) live with CDE using the shell in the password
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file to run its startup scripts. If you have changed your shell to bash,
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there is code in the CDE startup files (on Solaris, at least) to do the
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right thing.
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`dtterm' claims to use $SHELL as the default program to start, so if you
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can change $SHELL in the CDE startup files, you should be able to use bash
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in your terminal windows.
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Setting DTSOURCEPROFILE in ~/.dtprofile will cause the `Xsession' program
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to read your login shell's startup files. You may be able to use bash for
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the rest of the CDE programs by setting SHELL to bash in ~/.dtprofile as
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well, but I have not tried this.
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You can use the above `exec' recipe to start bash when not logging in with
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CDE by testing the value of the DT variable:
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if [ -n "$DT" ]; then
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[ -f /usr/gnu/bin/bash ] && exec /usr/gnu/bin/bash --login
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fi
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A8) I just changed my login shell to bash, and now I can't FTP into my
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machine. Why not?
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@ -324,16 +374,59 @@ Reference Manual.
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Section B: The latest version
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B1) What's new in version 2.03?
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B1) What's new in version 2.04?
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Bash-2.03 has a very few new features, in keeping with the convention
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Bash-2.04 contains the following new features (see the manual page for
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complete descriptions and the CHANGES and NEWS files in the bash-2.04
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distribution):
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o Programmable word completion with the new `complete' and `compgen' builtins;
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examples are provided in examples/complete/complete-examples
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o `history' has a new `-d' option to delete a history entry
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o `bind' has a new `-x' option to bind key sequences to shell commands
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o The prompt expansion code has new `\j' and `\l' escape sequences
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o The `no_empty_command_completion' shell option, if enabled, inhibits
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command completion when TAB is typed on an empty line
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o `help' has a new `-s' option to print a usage synopsis
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o New arithmetic operators: var++, var--, ++var, --var, expr1,expr2 (comma)
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o New ksh93-style arithmetic for command:
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for ((expr1 ; expr2; expr3 )); do list; done
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o `read' has new options: `-t', `-n', `-d', `-s'
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o The redirection code handles several filenames specially: /dev/fd/N,
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/dev/stdin, /dev/stdout, /dev/stderr
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o The redirection code now recognizes /dev/tcp/HOST/PORT and
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/dev/udp/HOST/PORT and tries to open a TCP or UDP socket, respectively,
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to the specified port on the specified host
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o The ${!prefix*} expansion has been implemented
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o A new FUNCNAME variable, which expands to the name of a currently-executing
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function
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o The GROUPS variable is no longer readonly
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o A new shopt `xpg_echo' variable, to control the behavior of echo with
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respect to backslash-escape sequences at runtime
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o The NON_INTERACTIVE_LOGIN_SHELLS #define has returned
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The version of Readline released with Bash-2.04, Readline-4.1, has several
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new features as well:
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o Parentheses matching is always compiled into readline, and controllable
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with the new `blink-matching-paren' variable
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o The history-search-forward and history-search-backward functions now leave
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point at the end of the line when the search string is empty, like
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reverse-search-history, and forward-search-history
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o A new function for applications: rl_on_new_line_with_prompt()
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o New variables for applications: rl_already_prompted, and rl_gnu_readline_p
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A short feature history dating from bash-2.0:
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Bash-2.03 had very few new features, in keeping with the convention
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that odd-numbered releases provide mainly bug fixes. A number of new
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features were added to Readline, mostly at the request of the Cygnus
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folks.
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a new shopt option, `restricted_shell', so that startup files can test
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A new shopt option, `restricted_shell', so that startup files can test
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whether or not the shell was started in restricted mode
|
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filename generation is now performed on the words between ( and ) in
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Filename generation is now performed on the words between ( and ) in
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compound array assignments (this is really a bug fix)
|
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OLDPWD is now auto-exported, as POSIX.2 requires
|
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ENV and BASH_ENV are read-only variables in a restricted shell
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@ -342,7 +435,7 @@ Bash may now be linked against an already-installed Readline library,
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All shells begun with the `--login' option will source the login shell
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startup files, even if the shell is not interactive
|
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There are lots of changes to the version of the Readline library released
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There were lots of changes to the version of the Readline library released
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along with Bash-2.03. For a complete list of the changes, read the file
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CHANGES in the Bash-2.03 distribution.
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@ -412,11 +505,11 @@ grammar tighter and smaller (66 reduce-reduce conflicts gone)
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lots of code now smaller and faster
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test suite greatly expanded
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B2) Are there any user-visible incompatibilities between bash-2.03 and
|
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B2) Are there any user-visible incompatibilities between bash-2.04 and
|
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bash-1.14.7?
|
||||
|
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There are a few incompatibilities between version 1.14.7 and version 2.03.
|
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They are detailed in the file COMPAT in the bash-2.03 distribution.
|
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There are a few incompatibilities between version 1.14.7 and version 2.04.
|
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They are detailed in the file COMPAT in the bash-2.04 distribution.
|
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|
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Section C: Differences from other Unix shells
|
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|
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|
|
@ -431,13 +524,15 @@ Things bash has that sh does not:
|
|||
`!' reserved word to invert pipeline return value
|
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`time' reserved word to time pipelines and shell builtins
|
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the `function' reserved word
|
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the select compound command and reserved word
|
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the `select' compound command and reserved word
|
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arithmetic for command: for ((expr1 ; expr2; expr3 )); do list; done
|
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new $'...' and $"..." quoting
|
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the $(...) form of command substitution
|
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the $(<filename) form of command substitution, equivalent to
|
||||
$(cat filename)
|
||||
the ${#param} parameter value length operator
|
||||
the ${!param} indirect parameter expansion operator
|
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the ${!param*} prefix expansion operator
|
||||
the ${param:length[:offset]} parameter substring operator
|
||||
the ${param/pat[/string]} parameter pattern substitution operator
|
||||
expansions to perform substring removal (${p%[%]w}, ${p#[#]w})
|
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|
|
@ -448,16 +543,18 @@ Things bash has that sh does not:
|
|||
ENV, PS3, PS4, DIRSTACK, PIPESTATUS, HISTSIZE, HISTFILE,
|
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HISTFILESIZE, HISTCONTROL, HISTIGNORE, GLOBIGNORE, GROUPS,
|
||||
PROMPT_COMMAND, FCEDIT, FIGNORE, IGNOREEOF, INPUTRC,
|
||||
SHELLOPTS, OPTERR, HOSTFILE, TMOUT, histchars, auto_resume
|
||||
SHELLOPTS, OPTERR, HOSTFILE, TMOUT, FUNCNAME, histchars,
|
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auto_resume
|
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DEBUG trap
|
||||
variable arrays with new compound assignment syntax
|
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redirections: <>, &>, >|
|
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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.
|
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export -n/-f/-p/name=value, pwd -L/-P, read -e/-p/-a,
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export -n/-f/-p/name=value, pwd -L/-P,
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read -e/-p/-a/-t/-n/-d/-s,
|
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readonly -a/-f/name=value, trap -l, set +o,
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set -b/-m/-o option/-h/-p/-B/-C/-H/-P,
|
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unset -f/-v, ulimit -m/-p/-u,
|
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|
|
@ -473,12 +570,13 @@ Things bash has that sh does not:
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|||
process substitution
|
||||
aliases and alias/unalias builtins
|
||||
local variables in functions and `local' builtin
|
||||
readline and command-line editing
|
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readline and command-line editing with programmable completion
|
||||
command history and history/fc builtins
|
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csh-like history expansion
|
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other new bash builtins: bind, command, builtin, declare/typeset,
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dirs, enable, fc, help, history, logout,
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popd, pushd, disown, shopt, printf
|
||||
other new bash builtins: bind, command, compgen, complete, builtin,
|
||||
declare/typeset, dirs, enable, fc, help,
|
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history, logout, popd, pushd, disown, shopt,
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printf
|
||||
exported functions
|
||||
filename generation when using output redirection (command >a*)
|
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POSIX.2-style globbing character classes
|
||||
|
|
@ -489,6 +587,8 @@ 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,
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||||
/dev/tcp/host/port, /dev/udp/host/port
|
||||
|
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Things sh has that bash does not:
|
||||
uses variable SHACCT to do shell accounting
|
||||
|
|
@ -521,11 +621,13 @@ 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,
|
||||
|
|
@ -533,18 +635,19 @@ 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
|
||||
|
|
@ -552,10 +655,11 @@ 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
|
||||
co-processes (|&, >&p, <&p)
|
||||
weirdly-scoped functions
|
||||
typeset +f to list all function names without definitions
|
||||
|
|
@ -574,30 +678,29 @@ Implementation differences:
|
|||
|
||||
C3) Which new features in ksh-93 are not in bash, and which are?
|
||||
|
||||
New things in ksh-93 not in bash-2.03:
|
||||
New things in ksh-93 not in bash-2.04:
|
||||
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-2.03:
|
||||
?: 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]},
|
||||
${!param*}
|
||||
compound array assignment
|
||||
the `!' reserved word
|
||||
loadable builtins -- but ksh uses `builtin' while bash uses `enable'
|
||||
|
|
@ -607,6 +710,7 @@ New things in ksh-93 present in bash-2.03:
|
|||
set -o notify/-C
|
||||
changes to kill builtin
|
||||
read -A (bash uses read -a)
|
||||
read -t/-d
|
||||
trap -p
|
||||
exec -c/-a
|
||||
`.' restores the positional parameters when it completes
|
||||
|
|
@ -638,7 +742,7 @@ the following function definition to your .bashrc:
|
|||
|
||||
which()
|
||||
{
|
||||
builtin type -p "$@"
|
||||
builtin type "$@"
|
||||
}
|
||||
|
||||
If you're moving from tcsh and would like to bring `where' along
|
||||
|
|
@ -771,8 +875,8 @@ descriptor 2.
|
|||
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
|
||||
-------------- ---------------
|
||||
|
|
@ -784,6 +888,14 @@ 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 $FCEDIT
|
||||
|
||||
Section E: How can I get bash to do certain things, and why does bash do
|
||||
things the way it does?
|
||||
|
||||
|
|
@ -835,62 +947,7 @@ You can build a version of bash that will not report SIGPIPE errors
|
|||
by uncommenting the definition of DONT_REPORT_SIGPIPE in the file
|
||||
config-top.h.
|
||||
|
||||
E3) How can I get bash to read and display eight-bit characters?
|
||||
|
||||
This is a process requiring several steps.
|
||||
|
||||
First, you must ensure that the `physical' data path is a full eight
|
||||
bits. For xterms, for example, the `vt100' resources `eightBitInput'
|
||||
and `eightBitOutput' should be set to `true'.
|
||||
|
||||
Once you have set up an eight-bit path, you must tell the kernel and
|
||||
tty driver to leave the eighth bit of characters alone when processing
|
||||
keyboard input. Use `stty' to do this:
|
||||
|
||||
stty cs8 -istrip -parenb
|
||||
|
||||
For old BSD-style systems, you can use
|
||||
|
||||
stty pass8
|
||||
|
||||
You may also need
|
||||
|
||||
stty even odd
|
||||
|
||||
Finally, you need to tell readline that you will be inputting and
|
||||
displaying eight-bit characters. You use readline variables to do
|
||||
this. These variables can be set in your .inputrc or using the bash
|
||||
`bind' builtin. Here's an example using `bind':
|
||||
|
||||
bash$ 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.
|
||||
|
||||
E4) 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.
|
||||
|
||||
E5) 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
|
||||
|
|
@ -906,38 +963,7 @@ 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.
|
||||
|
||||
E6) 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.
|
||||
|
||||
E7) 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
|
||||
|
|
@ -993,13 +1019,13 @@ this.
|
|||
This is the general approach -- in most cases you will not need to
|
||||
set $IFS to a different value.
|
||||
|
||||
E8) 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
|
||||
|
|
@ -1013,7 +1039,11 @@ 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.
|
||||
|
||||
E9) 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
|
||||
|
|
@ -1028,38 +1058,6 @@ 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.
|
||||
|
||||
E10) 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'
|
||||
|
||||
Section F: Things to watch out for on certain Unix versions
|
||||
|
||||
F1) Why can't I use command line editing in my `cmdtool'?
|
||||
|
|
@ -1156,16 +1154,211 @@ 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-2.03 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-2.04 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?
|
||||
|
||||
G1) How do I report bugs in bash, and where should I look for fixes and
|
||||
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?
|
||||
|
||||
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
|
||||
|
|
@ -1183,7 +1376,7 @@ and problems also take place there.
|
|||
To reach the bash maintainers directly, send mail to
|
||||
bash-maintainers@gnu.org.
|
||||
|
||||
G2) 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:
|
||||
|
|
@ -1213,36 +1406,33 @@ 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.
|
||||
|
||||
G3) 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/tcsh
|
||||
a bash debugger (a minimally-tested version is included with bash-2.04)
|
||||
associative arrays
|
||||
|
||||
G4) 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 way to bind readline editing key sequences to shell commands
|
||||
a mechanism to open network connections and assign them to file descriptors
|
||||
using redirection (like ksh /dev/{tcp,udp})
|
||||
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)
|
||||
|
||||
G5) When will the next release appear?
|
||||
H5) When will the next release appear?
|
||||
|
||||
The next version will appear sometime in 1999. Never make
|
||||
The next version will appear sometime in 2000 or 2001. Never make
|
||||
predictions.
|
||||
|
||||
|
||||
This document is Copyright 1995-1999 by Chester Ramey.
|
||||
This document is Copyright 1995-2000 by Chester Ramey.
|
||||
|
||||
Permission is hereby granted, without written agreement and
|
||||
without license or royalty fees, to use, copy, and distribute
|
||||
|
|
|
|||
Loading…
Add table
Add a link
Reference in a new issue