[color=red]I.GENERAL QUESTIONS
[/color][color=blue]
Q1.What is KornShell?[/color]
A1.KornShell is a command and scripting language
that is a superset of the System V UNIX shell,
aka, BourneShell (or 'sh').
[color=blue]
Q2.What is ksh?[/color]
A2.ksh is the name of the program that implements the
KornShell language.
[color=blue]
Q3.What is the history of ksh?[/color]
A3.ksh was written by David Korn at Bell Telephone Laboratories.
David Korn is currently at AT&T Laboratories.
The first version of ksh was in 1983. It was the first
shell to have command line editing with both emacs
and vi style interaction. The 1986 version was the first
to offer multibyte support. The 1988 version of ksh
is the version that was adopted by System V Release 4 UNIX
and was a source document for the IEEE POSIX and ISO
shell standards. The 1993 version is a major rewrite
of the 1988 version and focuses more on scripting.
[color=blue]
Q4.Where is the official description of the KornShell language?
[/color]A4.The Bolsky and Korn book, "The KornShell Command and Programming
Language", published by Prentice Hall, defines the 1988
version. The newer Bolsky and Korn book, "The New KornShell Command
and Programming Language", also published by Prentice Hall,
describes the 1993 version.
[color=blue]
Q5.What are the major new features of KornShell 1993?
[/color]A5.The only major new interactive feature is key binding.
Major new language features are floating point arithmetic,
associative arrays, complete ANSI-C printf, name reference
variables, new expansion operators, dynamic loading of
built-in commands, active variables, and compound variables.
Active and compound variables allow shell variables to
behave like objects. In addition, ksh93 has been written to be
extensible with an C language API for programming extensions.
[color=blue]
Q6.Are any further releases of ksh planned?
[/color]A6.Yes, we are in the process of planning for a newer version,
ksh200X. We are interested in suggestions for new features.
Again, most of the focus will be on scripting and reusability.
[color=blue]
Q7.What new features are planned for ksh200X?
[/color]A7.We are in the early stage of planning but the likely additions
are namespaces, an inheritance mechanism for objects,
and support for binary objects. Support for multi-threading
is also being considered.
[color=blue]
Q8.Is KornShell public domain?[/color]
A8.Yes, the language description is public domain and
can be reimplemented. Some of the KornShell language
features have been reimplemented in the GNU shell, bash
and in pdksh, a public domain implementation.
[color=blue]
Q9.Is ksh public domain?[/color]
A9.No, earlier versions were owned by both AT&T and Novell.
The 1993 version is owned by both Lucent and AT&T.
[color=blue]
Q10.Is source code available?
[/color]A10.Starting in March 2000, the ksh93 source is available
as part of a larger collection of software called
the ast-open software package which can be downloaded
from the site http://www.research.att.com/sw/download.
[color=blue]
Q11.What are the licensing terms?
[/color]A11.The exact license terms can be found in
http://www.research.att.com/sw/license/ast-open.html
[color=blue]
Q12.Does the license allow binaries to be freely redistributed?
[/color]A12.Yes, provided you make the license terms available to
everyone you distribute binaries to.
[color=blue]
Q13.If I make changes to the code, do I have to make them public?
[/color]A13.No, you do not have to make them public. However, if you
distribute the changes, you must allow us to be able
to get these changes and distribute them along with the source.
[color=blue]
Q14.Why do most vendors ship ksh88, not ksh93?
[/color]A14.Since ksh88 was included in System V release 4, most vendors
have just included this version. A separate license was
required for ksh93 from either Lucent or AT&T. We hope this
situation changes with the release of ksh93 in open source form.
[color=blue]
Q15.Do you provide support for ksh?
[/color]A15.No, we will try to fix any bugs we hear about in future
releases, but we do not provide any official support.
[color=blue]
Q16.Is ksh supported commercially?
[/color]A16.Global Technologies, Ltd, http://www.gtlinc.com, distributes
and supports the "Common Operating Environment" which includes
ksh all of the other ast-open tools. They support it across
a broad range of systems. Software vendors that supply ksh with
their systems typically support it for that system.
[color=blue]
Q17.What is pdksh and is it related to ksh or KornShell?
[/color]A17.pdksh is a public domain version of a UNIX shell that is
unrelated to ksh. It supports most of the 1988
KornShell language features and some of the 1993 features.
Some KornShell scripts will not run with pdksh.
[color=blue]
Q18.How is the MKS Toolkit Kornshell related to KornShell?
[/color]A18.MKS Tookit Kornshell is a completely independent implementation
that supports a subset of the 1988 KornShell language.
[color=blue]
Q19.What systems does ksh run on?
[/color]A19.ksh has been written to be portable. It has been ported
to virtually every known UNIX system. In addition it runs
on non-UNIX systems such as IBM's MVS using OpenEdition, and
Microsoft's Windows 9X, Windows NT and Windows 2000.
ksh is part of the UWIN (Unix for Windows) software,
http://www.research.att.com/sw/tools/uwin.
[color=blue]
Q20.Does ksh conform to the IEEE POSIX and ISO shell standard?
[/color]A20.The 1993 version should conform to the 1992 standard. At one
point it had passed the test suite created by X/OPEN.
[color=blue]
Q21.Will KornShell 88 scripts run with KornShell 93?
[/color]A21.In almost all cases, the answer is yes. However,
the IEEE POSIX and ISO standards required a few
changes that could cause scripts to fail. There is a
separate document that lists all known incompatibilities.
[color=blue]
Q22.Can ksh run as /bin/sh?
[/color]A22.We have installed ksh as /bin/sh on several systems without
encountering any problems. Our Linux systems use this
instead of bash.
=====================================================
[ 本帖最后由 寂寞烈火 于 2005-11-20 23:42 编辑 ]
寂寞烈火 回复于：2005-11-20 18:42:38
[color=red]II.INTERACTIVE SHELL QUESTIONS
[/color][color=blue]
Q1.How do I get separate history files for shell?[/color]
A1.ksh uses a shared history file for all shells that
use the same history file name. This means
that commands entered in one window will be seen by
shells in other windows. To get separate windows,
the HISTFILE variable needs to be set to different name
before the first history command is created.
[color=blue]
Q2.Why does the screen width not function correctly when non-printing characters are in my prompt?[/color]
A2.The shell computes the screen width by subtracting the width of
the prompt from the screen width. To account for non-printing
characters, for example escape sequences that display in the title
bar, follow these characters with a carriage return. The shell
starts recomputing the width after each carriage return.
[color=blue]
Q3.What is the PS4 prompt and how is it used?[/color]
A3.The PS4 prompt is evaluated and displayed before each line when
running an execution trace. If unset, a + and a <space> will
be output before each line in the trace. Putting '$LINENO'
inside PS4 will cause the line number to be displayed. Putting
'$SECONDS' in the PS4 prompt will cause the elapsed time
to be displayed before each line. Note that single quotes
are used to prevent the expansion from happening when PS4
is defined.
[color=blue]
Q4.How is keybinding done?[/color]
A4.ksh93 provides a KEYBD trap that gets executed whenever a key
is entered from the keyboard. Using this trap, and the associate
array feature of ksh93, a keybind function can easily be written
which will map any entered key sequence to another key sequence.
[color=blue]
Q5.How do I get the arrow keys to work?[/color]
A5.Starting with the 'h' point release, on most keyboards you
do not have to do anything to get the arrow keys to work.
However, if they do not generate standard escape sequences,
then you will have to use a keybinding function to get them
to work.
[color=blue]
Q6.Does ksh support file name completion?[/color]
A6.Yes, it does. The default key binding is <ESC><ESC>
however, starting with the 'g' point release, <TAB> also works
for completion. Note, the vi users need to set -o viraw
in order to get <TAB> completion to work.
[color=blue]
Q7.Does ksh support command completion?[/color]
A7.If you perform completion on the first word of a command,
ksh will do completion using aliases, functions, and commands.
[color=blue]
Q8.Is completion programmable?[/color]
A8.Yes, using the key binding mechanism, you can script the behavior
of any key and therefore cause the current contents of any
line to be replaced by any other line.
[color=blue]
Q9.Is there any way to get the command-line editor to go to more than a single line?[/color]
A9.In vi-mode, if you hit 'v' while in control mode, it will bring
up a full screen version of vi on the current command. The command
will execute when you exit vi.
[color=blue]
Q10.Can I use the shell line editor on other commands?[/color]
A10.The command ie, that comes along with shell, can be used
to run line input oriented commands with command line editing.
[color=blue]
Q11.When I do echo 0, I am getting 267. What does this mean?[/color]
A11.ksh93 reports process that terminate with a signal as 256+signo.
Earlier versions used 128+signo but this makes it impossible
to distinguish from a command exit with that value. If you run
kill -l $?
on this signal number, it will give the the name of the signal
that caused this exit.
[color=blue]
Q12.When I type builtin, I notice that some of these are full pathnames. What does this mean?[/color]
A12.Builtins that are not bound to pathnames are always searched
for before doing a path search. Builtins that are bound
to pathnames are only executed when the path search would
bind to this pathname.
[color=blue]
Q13.What is a self generating man page?[/color]
A13.A self generating man page is one that is generated by the
option parser within that command using an extended version
of the getopts function. The man page can be generated in html,
troff, or directly for the terminal. Most builtin commands
in the shell have self generating man pages so that you
can run for example, kill --man or kill --html to get
the description of kill to the screen or as an html file.
This same method can also be used for shell scripts. Run
getopts --man for more details.
[color=blue]
Q14.What is autoloading?[/color]
A14.Autoloading was a method used in ksh88, and still permitted in ksh93
to declare that a name corresponded to a function. The function
would be loaded and executed when first referenced. This was
necessary since FPATH was always searched after PATH with ksh88
and therefore if you defined a function whose name was the same
as that of a program on your path, the program on your path
would have been executed. With ksh93, when a pathname is
encountered that is on PATH, but also is in FPATH, this directory
is assumed to be a function directory. Thus, you can have
function directories searched before program directories so
that autoloading is no longer needed.
=====================================================
[ 本帖最后由 寂寞烈火 于 2005-11-20 18:52 编辑 ]
寂寞烈火 回复于：2005-11-20 18:43:33
[color=red]III.SHELL PROGRAMMING QUESTIONS
[/color][color=blue]
Q1.What is the difference between * and @, for example, and ?[/color]
A1.When used outside of "", they are equivalent. However, within
double quotes, "$@" produces one argument for each positional
parameter, and "$* produces a single argument. Note that "$@"
preserves arguments lists, whereas $* may not unless both
word splitting and pathname expansion are disabled.
[color=blue]
Q2.Why do I need spaces around { and } but not around ( and )?[/color]
A2.The characters ( and ) are shell metacharacters and are always
treated specially. For historical reasons, { and } were
treated as reserved words and are only special as separate
words at locations in which a command can begin.
[color=blue]
Q3.How do I get read to maintain the characters?[/color]
A3.Use read -r instead.
Q4.How can a write a ksh script that responds directly to each
character so that you user just has to enter y, not y<return>?[/color]
A4.There are two ways to do this. The easiest is to use
read -n1 x
Alternatively, you could do
function keytrap
{
.sh.edchar=${sh.edchar}$'n'
}
trap keytrap KEYBD
and then
read x
[color=blue]
Q5.What is the purpose of $'...'?[/color]
A5.The $'...' option was added to ksh93 to solve the problem
of entering special characters in scripts. It uses
ANSI-C rules to translate the string between the '...'.
It would have been cleaner to have all "..." strings handle
ANSI-C escapes, but that would not be backwards compatible.
[color=blue]
Q6.What is the -n option used for?[/color]
A6.You should always run ksh -n on each script you write. The -n
option will check for syntax errors on paths that might not
even be checked when you run the script. It also produces
a number of warning messages.
[color=blue]
Q7.Why are both `...` and $(...) used for command substitution?[/color]
A7.The `...` method has some rather strange quoting rules
and does not nest easily. $(...) was added to ksh88 to
make command substitution easy to use. `...` is provided
for backwords compatibility only.
[color=blue]
Q8.How can I tell if all the commands of a pipeline have succeeded?[/color]
A8.The pipefail option was added to the 'g' point release of ksh93.
With pipefail set, a pipeline will fail if any element of the
pipeline fails. The exit status will be that of the first
command that has failed.
[color=blue]
Q9.How do I connect to a socket from a shell script?[/color]
A9.exec 3<> /dev/tcp/hostname/portnum
will open a tcp connection to portnum on hostname for
reading and writing on file descriptor 3. You can then
use read and print statements with file descriptor 3,
or redirection operators <&3 or >&3 to use these connections.
[color=blue]
Q10.What is the difference between [...] and [[...]]?[/color]
A10.The [[...]] is processed as part of the shell grammar
whereas [...] is processed like any other command.
Operators and operands are detected when the command is
read, not after expansions are performed. The shell does not
do word splitting or pathname generation inside [[...]].
This allows patterns to be specified for string matching
purposes.
[color=blue]
Q11.How come [[ $foo == $bar ]] is true and [[ $bar == $foo ]] is false?[/color]
A11.The == operator is not symmetrical. It takes a string on the left
and a pattern on the right. However, if you double quote the right
hand side, which removes the special meaning of pattern match
characters, then this becomes a string comparison so that
[[ "$foo" == "bar" ]] and [[ "$bar" == "$foo" ]] are equivalent.
[color=blue]
Q12.Why does have print since echo already exists is is widely used?[/color]
A12.The behavior of echo varies from system to system.
The POSIX standard does not define the behavior of echo when
the first argument beings with a - or when any argument
contains a character. This makes echo pretty useless for
use in portable scripts.
[color=blue]
Q13.What is $bar after,echo foo | read bar?[/color]
A13.The is foo. ksh runs the last component of a pipeline
in the current process. Some shells run it as a subshell
as if you had invoked it as echo foo | (read bar).
[color=blue]
Q14.What is the difference between ((expr)) and $((expr))?[/color]
A14.((expr)) is a command that evaluates an arithmetic expression.
The exit status of this command is 0 if the expression
evaluates to non-zero and is 1 if it evaluates to 0.
0 is an string expansion that expands to a string
representation of the value of this arithmetic expression.
It can be used anywhere a variable substitution is premitted.
[color=blue]
Q15.What is the difference between $((x*y)) and $(($x*$y))?[/color]
A15.In the first case the value of x and the value of y are multiplied
together, and then their result is converted to a string. In the
second case variables $x, *, and $y are concatenated to form
an arithmetic expression which is then evaluated. This can
yield different results, for example,
x=2+3 y=4+5
print $((x*y)) $(($x*$y))
45 19
[color=blue]
Q16.How do I handle filenames with spaces in them?[/color]
A16.To be POSIX conforming, ksh has to do word splitting and
pathname expansion the results of substitutions. You can
enclose variable substitutions in "..." to prevent both
word splitting and pathname expansion. Alternatively,
you can disable word splitting by setting IFS='' and
pathname generation with set -o noglob.
[color=blue]
Q17.What are active variables?[/color]
A17.By default shell variables are passive. They hold values
given to them on assignment, and return values on reference.
Active variables allow the assignment and reference (and
other actions) be controlled by functions specific to that
variable. At the shell level, a 'get', 'set', or 'unset'
shell function can be defined for any variable to make them
active, so that the function foo.set will be invoked whenever
the variable foo is assigned a value. At the C interface
level, several functions can be stacked together for an
active variable.
[color=blue]
Q18.What is the difference between function name and name()?[/color]
A18.In ksh88 these were the same. However, the POSIX standard
choose foo() for functions and defined System V Release 2
semantics to them so that there are no local variables
and so that traps are not scoped. ksh93 keeps the ksh88
semantics for functions defined as function name, and
has changed the name() semantics to match the POSIX
semantics. Clearly, function name is more useful.
[color=blue]
Q19.What are name reference variables and how are they used?[/color]
A19.Reference variables are variables in which all references
and assignments refer to the variable that they reference.
For example,
typeset -n name=$1
name=value
is equivalent to
eval $1='value'
References are most useful for passing arguments such as
arrays to functions.
[color=blue]
Q20.If i=1 and var1=some value, how do I print vartt to get its value?[/color]
A20.Either use
eval print var$i
or
typeset -n x=var$i
print $x
[color=blue]
Q21.How can I shift the elements of an array?[/color]
A21.The shift special builtin-command only works for positional
parameters. However, noting that array subscripts start at 0,
you can use
set -A name "${name[@]:1}"
to shift the array.
[color=blue]
Q22.Why are the braces required with array references, e. g. ${x[1]}?[/color]
A22.It would be nice to do $x[1], but the POSIX shell would expand $x
and then search for the file pattern resulting by concatenating [1].
ksh is POSIX compatible.
[color=blue]
Q23.How do I get the list of subscript names for an associative array?[/color]
A23.The prefix operator ! in variable expansions can be used to
get names. To get the names of subscripts for an array, associative
or indexed, use ${!var[@]}.
[color=blue]
Q24.How do I do global substitutions on the contents of shell variables?[/color]
A24.Use // instead of / for global substitution, ${var//aa/bb} will
expand to the value of with each "aa" replace by "bb".
[color=blue]
Q25.How can I convert %XX values to ascii?[/color]
A25.You can convert this to a sequence of ANSI C strings and then eval that
string, for example suppose the variable 'foo' contains %XX strings,
then
eval print -r -- "$'${foo//'%'@(??)/'x1"'$'"}'"
will print out the string in ascii.
[color=blue]
Q26.I want to use exec to open a file. How do I prevent the script from exiting if the exec fails?[/color]
A26.If you run
command exec ... || error ...
then error will be executed if the exec fails, but the script
will not terminate. The command builtin will prevent the shell
from exiting when special built-ins fail.
[color=blue]
Q27.How do I execute a builtin inside a function of the same name?[/color]
A27.You use the command builtin for this. For example,
function cd
{
command cd "$@" && title "$PWD"
}
will run the builtin command cd from within the function cd
rather than calling the function cd recursively.
[color=blue]
Q28.How are variables scoped in ksh?[/color]
A28.The scoping of variables was not defined for ksh88 but in ksh93
static scoping was specified. For example the output from
function f1
{
print foo=$foo
}
function f2
{
typeset foo=local
f1
}
foo=global
f2
will be "global". To get f2 to cause f1 to print the local
value of foo, f2 can run "foo=$foo f1" instead.
[color=blue]
Q29.Can you write a self reproducing program in KornShell?[/color]
A29.Yes, the following program is self reproducing. Any shorter ones?
n="
" q="'" x="cat <<-!" y=! z='n="$n" q="$q" x="$x" y=$y z=$q$z$q$n$x$n$z$n$y'
cat <<-!
n="$n" q="$q" x="$x" y=$y z=$q$z$q$n$x$n$z$n$y
!
=====================================================
[ 本帖最后由 寂寞烈火 于 2005-11-20 18:59 编辑 ]
寂寞烈火 回复于：2005-11-20 18:45:05
[color=red]IV.SHELL EXTENSIONS
[/color][color=blue]
Q1.Is there a shell compiler?[/color]
A1.There is a separate command named shcomp that will convert
a script into an intermediate machine independent form. The shell
will detect this format whenever it runs a script and execute
directly from this intermediate format.
[color=blue]
Q2.What is the advantage of making commands built-in?[/color]
A2.The startup time is reduced by a couple of orders of
magnitude. In addition, built-in commands can access
ksh internals.
[color=blue]
Q3.What is the disadvantage of making commands built-in?[/color]
A3.Errors in these built-ins can cause the shell to crash.
[color=blue]
Q4.How do I add built-in commands?[/color]
A4.There are two ways to do this. One is write a shared library
with functions whose names are b_xxxx where xxxx is the name of
the builtin. The function b_xxxx takes three argument. The first
two are the same as a mail program. The third parameter is
a pointer argument which will point to the current shell context.
The second way is to write a shared library with a function named
lib_init(). This function will be called with an argument of 0
after the library is loaded. This function can add built-ins
with the sh_addbuiltin() API function. In both cases, the
library is loaded into the shell with the "builtin" utility.
[color=blue]
Q5.Can ksh93 be embedded?[/color]
A5.Yes, ksh93 can be compiled as a shared or dynamically linked
library which can be embedded into applications. There is
an API for interfacing to shell variables and to several of
the internal shell functions.
[color=blue]
Q6.Can I write GUI applications with ksh?[/color]
A6.There are two extensions to ksh that can be used to write
GUI applications as shell script. One is dtksh which
was written by Steve Pendergrast at Novell and is
included with the Common Desktop Environment, CDE. The other is
tksh which was written by Jeff Korn. tksh combines the tk graphics
package with ksh93 and reimplements the tcl language
as an extension so that both tcl and ksh scripts
can run in the same address space. The source for tksh
is included in the ast-open package.
[ 本帖最后由 寂寞烈火 于 2005-11-20 19:00 编辑 ]
dbcat 回复于：2005-11-20 18:50:53
精华!
用英文写了蛮久吧?:mrgreen::mrgreen:
大蚂蚁 回复于：2005-11-20 19:18:21
:roll:为啥我看的时候好像有很多蝌蚪再动:roll:
寂寞烈火 回复于：2005-11-20 23:38:23
引用：原帖由 大蚂蚁 于 2005-11-20 19:18 发表
:roll:为啥我看的时候好像有很多蝌蚪再动:roll:
这个文档很经典的,时常看看,应该有所帮助的
BTW: :em11::em11:
yuyuyou 回复于：2005-11-20 23:54:18
烈火兄辛苦了！
要是有中文的就好了。
唉，先收下，还bash呢，ksh。。。。。。。。。。。。。。。。。。。。。
技安 回复于：2005-11-21 00:02:53
每个字母我好像都认识、
：P
委实是看不懂、
dbcat 回复于：2005-11-23 13:14:51
引用：原帖由 yuyuyou 于 2005-11-20 23:54 发表
烈火兄辛苦了！
要是有中文的就好了。
唉，先收下，还bash呢，ksh。。。。。。。。。。。。。。。。。。。。。
[size=5]BASH FAQ[/size]
This is the Bash FAQ, version 3.30, for Bash version 3.0.
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
[email]chet@po.cwru.edu[/email].
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
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 Shell and Utilities standard'?
A10) What is the bash `posix mode'?
Section B: The latest version
B1) What's new in version 3.0?
B2) Are there any user-visible incompatibilities between bash-3.0 and
bash-1.14.7?
Section C: Differences from other Unix shells
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?
D1) Why does bash run a different version of `command' than
`which command' says it will?
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 `|&'?
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: Why does bash do certain things the way it does?
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?
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?
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?
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'?
E10) Why does `cd //' leave $PWD as `//'?
E11) If I resize my xterm while another program is running, why doesn't bash
notice the change?
E12) Why don't negative offsets in substring expansion work like I expect?
Section F: Things to watch out for on certain Unix versions
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?
F3) Why does bash dump core after I interrupt username completion or
`~user' tilde expansion on a machine running NIS?
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?
F7) Why do bash-2.05a and bash-2.05b fail to compile `printf.def' on
HP/UX 11.x?
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 H: Where do I go from here?
H1) How do I report bugs in bash, and where should I look for fixes and
advice?
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?
dbcat 回复于：2005-11-23 13:16:30
----------
Section A: The Basics
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
shells.
Bash contains a number of enhancements over those shells, both
for interactive use and shell programming. Features geared
toward interactive use include command line editing, command
history, job control, aliases, and prompt expansion. Programming
features include additional variable expansions, shell
arithmetic, and a number of variables and options to control
shell behavior.
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.
A2) What's the latest version?
The latest version is 3.0, first made available on 27 July, 2004.
A3) Where can I get it?
Bash is the GNU project's shell, and so is available from 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 3.0:
ftp://ftp.gnu.org/pub/gnu/bash/bash-3.0.tar.gz
ftp://ftp.cwru.edu/pub/bash/bash-3.0.tar.gz
Formatted versions of the documentation are available with the URLs:
ftp://ftp.gnu.org/pub/gnu/bash/bash-doc-3.0.tar.gz
ftp://ftp.cwru.edu/pub/bash/bash-doc-3.0.tar.gz
Any patches for the current version are available with the URL:
ftp://ftp.cwru.edu/pub/bash/bash-3.0-patches/
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
exists is to type `configure' and then `make'. The build process
will attempt to discover the version of Unix you have and tailor
itself accordingly, using a script created by GNU autoconf.
More information appears in the file `INSTALL' in the distribution.
The Bash web page (http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html)
explains how to obtain binary versions of bash for most of the major
commercial Unix systems.
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-2.05 and later
versions 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 (now part of Red Hat) as part
of their CYGWIN project. For more information about the project, see
http://www.cygwin.com/.
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-2.05b to the CYGWIN environment, and it is available as
part of their current release. Bash-3.0 is currently being tested and
should be available soon.
Bash-2.05b and later versions should require no local Cygnus changes to
build and run under CYGWIN.
DJ Delorie has a port of bash-2.x 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.
Mark Elbrecht <[email]snowball3@bigfoot.com[/email]> has sent me notice that bash-2.04
is available for DJGPP V2. The files are available as:
ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204b.zip binary
ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204d.zip documentation
ftp://ftp.simtel.net/pub/simtelnet/gnu/djgpp/v2gnu/bsh204s.zip source
Mark began to work with bash-2.05, but I don't know the current status.
Bash-3.0 compiles and runs with no modifications under Microsoft's Services
for Unix (SFU), once known as Interix.
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.
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
you, that's all you need. Note that many systems require the full
pathname to a shell to appear in /etc/shells before you can make it
your login shell. For this, you may need the assistance of your
friendly local system administrator.
If you cannot do this, you can still use bash as your login shell, but
you need to perform some tricks. The basic idea is to add a command
to your login shell's startup file to replace your login shell with
bash.
For example, if your login shell is csh or tcsh, and you have installed
bash in /usr/gnu/bin/bash, add the following line to ~/.login:
if ( -f /usr/gnu/bin/bash ) exec /usr/gnu/bin/bash --login
(the `--login' tells bash that it is a login shell).
It's not a good idea to put this command into ~/.cshrc, because every
csh you run without the `-f' option, even ones started to run csh scripts,
reads that file. If you must put the command in ~/.cshrc, use something
like
if ( $?prompt ) exec /usr/gnu/bin/bash --login
to ensure that bash is exec'd only when the csh is interactive.
If your login shell is sh or ksh, you have to do two things.
First, create an empty file in your home directory named `.bash_profile'.
The existence of this file will prevent the exec'd bash from trying to
read ~/.profile, and re-execing itself over and over again. ~/.bash_profile
is the first file bash tries to read initialization commands from when
it is invoked as a login shell.
Next, add a line similar to the above to ~/.profile:
[ -f /usr/gnu/bin/bash ] && [ -x /usr/gnu/bin/bash ] &&
exec /usr/gnu/bin/bash --login
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.
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) that attempts
to do the right thing. It is, however, often broken, and may require that
you use the $BASH_ENV trick described below.
`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
If CDE starts its shells non-interactively during login, the login shell
startup files (~/.profile, ~/.bash_profile) will not be sourced at login.
To get around this problem, append a line similar to the following to your
~/.dtprofile:
BASH_ENV=${HOME}/.bash_profile ; export BASH_ENV
and add the following line to the beginning of ~/.bash_profile:
unset BASH_ENV
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
noted in the answer to the previous question, many systems require
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.
dbcat 回复于：2005-11-23 13:17:28
Others :
http://cnswww.cns.cwru.edu/~chet/bash/FAQ
:mrgreen:
大蚂蚁 回复于：2005-11-23 13:27:46
:em15:麻烦美女把蝌蚪翻译成方块:em02:
dbcat 回复于：2005-11-23 13:32:39
引用：原帖由 大蚂蚁 于 2005-11-23 13:27 发表
:em15:麻烦美女把蝌蚪翻译成方块:em02:
还三角呢 :em12::em12:
大蚂蚁 回复于：2005-11-23 13:38:22
引用：原帖由 dbcat 于 2005-11-23 13:32 发表
还三角呢 :em12::em12:
:em06::em06::em06:
文档内容不算难，还可以看懂:em15:，都是最基础的东西，不过最好用 [ code]
框起来比较好点:em11: 有些变表情符号了:em24:
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