A's to Q's about BASH, the Bourne-Again SHell

Chet Ramey translated in sgml by charles vidal.

This document contains a set of frequently-asked questions concerning Bash, the GNU Bourne-Again Shell. Bash is a freely-available command interpreter with advanced features for both interactive use and shell programming.

Another good source of basic information about shells is the collection of FAQ articles periodically posted to comp.unix.shell.

Questions and comments concerning this document should be sent to het@po.cwru.edu.

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 Summary: A's to Q's about BASH, the Bourne-Again SHell Originator: het@odin URL: ftp://ftp.cwru.edu/pub/bash/FAQ Maintainer: het@po.cwru.edu (Chet Ramey)

1. The Basics

• 1.1 What is it?
• 1.2 What's the latest version?
• 1.3 Where can I get it?
• 1.4 On what machines will bash run?
• 1.5 Will bash run on operating systems other than Unix?
• 1.6 How can I build bash with gcc?
• 1.7 How can I make bash my login shell?
• 1.8 I just changed my login shell to bash, and now I can't FTP into my
• 1.9 What's the `POSIX 1003.2 standard'?

2. The latest version

• 2.1 What's new in version 2.04?
• 2.2 Are there any user-visible incompatibilities between bash-2.04 and

3. Differences from other Unix shells

• 3.1 How does bash differ from sh, the Bourne shell?
• 3.2 How does bash differ from the Korn shell, version ksh88?
• 3.3 Which new features in ksh-93 are not in bash, and which are?

4. Why does bash do some things differently than other Unix shells?

• 4.1 Why does bash run a different version of `command' than
• 4.2 Why doesn't bash treat brace expansions exactly like csh?
• 4.3 Why doesn't bash have csh variable modifiers?
• 4.4 How can I make my csh aliases work when I convert to bash?
• 4.5 How can I pipe standard output and standard error from one command to
• 4.6 Now that I've converted from ksh to bash, are there equivalents to

5. How can I get bash to do certain things, and why does bash do

• 5.1 Why is the bash builtin `test' slightly different from /bin/test?
• 5.2 Why does bash sometimes say `Broken pipe'?
• 5.3 When I have terminal escape sequences in my prompt, why does bash
• 5.4 If I pipe the output of a command into `read variable', why doesn't
• 5.5 I have a bunch of shell scripts that use backslash-escaped characters
• 5.6 Why doesn't a while or for loop get suspended when I type ^Z?
• 5.7 What about empty for loops in Makefiles?

6. Things to watch out for on certain Unix versions

• 6.1 Why can't I use command line editing in my `cmdtool'?
• 6.2 I built bash on Solaris 2. Why do globbing expansions and filename
• 6.3 Why does bash dump core after I interrupt username completion or
• 6.4 I'm running SVR4.2. Why is the line erased every time I type `@'?
• 6.5 Why does bash report syntax errors when my C News scripts use a
• 6.6 Why can't I use vi-mode editing on Red Hat Linux 6.1?

7. How can I get bash to do certain common things?

• 7.1 How can I get bash to read and display eight-bit characters?
• 7.2 How do I write a function `x' to replace builtin command `x', but
• 7.3 How can I find the value of a shell variable whose name is the value
• 7.4 How can I make the bash `time' reserved word print timing output that
• 7.5 How do I get the current directory into my prompt?
• 7.6 How can I rename "*.foo" to "*.bar"?
• 7.7 How can I translate a filename from uppercase to lowercase?
• 7.8 How can I write a filename expansion (globbing) pattern that will match

8. Where do I go from here?

• 8.1 How do I report bugs in bash, and where should I look for fixes and
• 8.2 What kind of bash documentation is there?
• 8.3 What's coming in future versions?
• 8.4 What's on the bash `wish list' for future versions?
• 8.5 When will the next release appear?