Unix Shells : Differences a quick look!
posted 4 May 2009, Monday
Shell features
Do you know at a glance the differences from the Korn Shell to the BASH shell? Here is a quick table for your reference!
This is not comprehensive list but rather a good starting point to educate one's self. There is enough information here to make an educated decision as to which shell to use over another. The C Shell listed is specific to SUNOS 4.X as many vendors shell for production is either a tsch or their own enhanced version of C Shell. Either way, you should check what the script is for your system and determine how it fits in the table below:
(MAC USERS: The default shell, as shipped by Apple is the tcsh: I quickly change this to bash as it, in my opinion, has better features)
sh csh ksh bash tcsh zsh rc es
Job control N Y Y Y Y Y N N
Aliases N Y Y Y Y Y N N
Shell functions Y(1) N Y Y N Y Y Y
"Sensible" Input/Output redirection Y N Y Y N Y Y Y
Directory stack N Y Y Y Y Y F F
Command history N Y Y Y Y Y L L
Command line editing N N Y Y Y Y L L
Vi Command line editing N N Y Y Y(3) Y L L
Emacs Command line editing N N Y Y Y Y L L
Rebindable Command line editing N N N Y Y Y L L
User name look up N Y Y Y Y Y L L
Login/Logout watching N N N N Y Y F F
Filename completion N Y(1) Y Y Y Y L L
Username completion N Y(2) Y Y Y Y L L
Hostname completion N Y(2) Y Y Y Y L L
History completion N N N Y Y Y L L
Fully programmable Completion N N N N Y Y N N
Mh Mailbox completion N N N N(4) N(6) N(6) N N
Co Processes N N Y N N Y N N
Builtin artithmetic evaluation N Y Y Y Y Y N N
Can follow symbolic links invisibly N N Y Y Y Y N N
Periodic command execution N N N N Y Y N N
Custom Prompt (easily) N N Y Y Y Y Y Y
Sun Keyboard Hack N N N N N Y N N
Spelling Correction N N N N Y Y N N
Process Substitution N N N Y(2) N Y Y Y
Underlying Syntax sh csh sh sh csh sh rc rc
Freely Available N N N(5) Y Y Y Y Y
Checks Mailbox N Y Y Y Y Y F F
Tty Sanity Checking N N N N Y Y N N
Can cope with large argument lists Y N Y Y Y Y Y Y
Has non-interactive startup file N Y Y(7) Y(7) Y Y N N
Has non-login startup file N Y Y(7) Y Y Y N N
Can avoid user startup files N Y N Y N Y Y Y
Can specify startup file N N Y Y N N N N
Low level command redefinition N N N N N N N Y
Has anonymous functions N N N N N N Y Y
List Variables N Y Y N Y Y Y Y
Full signal trap handling Y N Y Y N Y Y Y
File no clobber ability N Y Y Y Y Y N F
Local variables N N Y Y N Y Y Y
Lexically scoped variables N N N N N N N Y
Exceptions N N N N N N N Y
Key to the table above.
Y Feature can be done using this shell.
N Feature is not present in the shell.
F Feature can only be done by using the shells function
mechanism.
L The readline library must be linked into the shell to enable
this Feature.
Notes to the table above
1. This feature was not in the orginal version, but has since become
almost standard.
2. This feature is fairly new and so is often not found on many
versions of the shell, it is gradually making its way into
standard distribution.
3. The Vi emulation of this shell is thought by many to be
incomplete.
4. This feature is not standard but unoffical patches exist to
perform this.
5. A version called 'pdksh' is freely available, but does not have
the full functionality of the AT&T version.
6. This can be done via the shells programmable completion mechanism.
7. Only by specifing a file via the ENV environment variable.