Recommended Shell - sh, csh or ksh : A Summary (LONG)

QQ11 at LIVERPOOL.AC.UK QQ11 at LIVERPOOL.AC.UK
Fri Nov 9 07:25:05 AEST 1990


[ this summary was produced by a colleague on whose behalf I posted the
  original question. Please do not mail/post if the summary does not
  fit in with your view of which shell is best. The summary is based on
  the mail received.
  Many thanks to all who replied ]

  Here's a summary of the comments made in response to the question

  "I  would  be interested to hear from any organisation, especially one
  with a research/teaching environment, who has decided on a  particular
  shell and why.

  I'm   interested   in   how  you  made  your  decision,  whether  more
  consideration went into interactive use than programming use,  whether
  the   choice  was  correct  with  hindsight  and  if  you  didn't  use
  sh/csh/ksh, which one did you select and why?"

  Of the replies received (so far 26) the shells recommended and in  use
  were:

                  Recommended               In Use
            Interactive Programming Interactive Programming
  ksh            10          8           8           7
  bash           6           4           1           1
  csh            2                       7           2
  sh             1           5           2           5
  clyde                      1                       1
  tcsh           1           1           2           1
  msh                        1           1
  perl                       1
  BRL's sh (R2)              1           1
  BRL's sh (R3)  1           1
  expect         1

  Listed below is a summary of the comments made about each shell.  They
  are  the views expressed by the respondents, not necessarily the views
  of the Liverpool University Computer Laboratory.

  1.  Bourne Shell

      o   is the standard UNIX shell.

      o   comes with every UNIX system.

      o   used for programming.  Compatible with all shells.

      o   fully parses the control structure.

      o   is very reliable.

      o   doesn't  have  either  history  recall   or   background   job
          capabilities.

      o   not  suitable for an interactive shell, not having any history
          mechanism or job control.

      o   with windowing sh is the most appropriate, because it's  small
          and  fast  therefore there isn't a large cost in starting up a
          new window.  Other shell have features which are not  required
          when using shells under a windowed environment.

      o   University of Bath (UK) currently gives the users sh by default.

      o   shows its age

  2.  Korn Shell

      o   is  basically a superset of sh, so sh users can easily migrate
          to ksh.

      o   largest gain over sh and csh is automatic command and filename
          completion.  Its control structures are also  supposed  to  be
          augmented,  and  it  pays  attention  to a more diverse set of
          user-settable environment-configuration variables.

      o   much better than csh from several major standpoints:

          -   has history editing - this is a big plus
          -   changes to keep up with things like  POSIX  standards  for
              shells, new features of the OS, etc.  Csh is stagnant.
          -   ksh  versions  are available for lots of machines, even if
              you don't have a source licence (if your  machine  doesn't
              have a csh binary, you have to have an AT&T source licence
              to get it, whereas, ksh source can be bought from the AT&T
              toolchest for $3,000).
          -   a  ksh  work-alike  is available in source absolutely free
              from GNU.
          -   csh users generally have to  learn  sh  syntax  anyway  to
              write  efficient  shell scripts and to read other people's
              scripts.

      o   programming is upward-compatible with /bin/sh.

      o   the interactive features were MUCH nicer than  csh's.    Alias
          and  ~user  have been stolen from csh, and the history editing
          is a friendly screen-editor-like approach using vi  or  emacs,
          and you also had a command-based history "r" or "r foo".

      o   No question about it, ksh is by far the superior shell..  Here
          at work, most people seem to like csh, since they come from an
          academic  environment,  but they are slowly being converted to
          ksh when they see  the  ease  of  recalling  and  editing  old
          commands..    Plus,  there  is the added advantage of it being
          compatible with the standard Bourne shell.

      o   ksh is probably the fastest of all of the shells.  It has  the
          good  sh  syntax  and  many of the good tcsh features.  It has
          some features that are not in any of the  other  shells  also.
          Since  it  is  upward  compatible  with  sh,  which  is mostly
          standard, there is no problem making it  portable,  since  you
          only pay for the features that you use.

      o   isn't available everywhere.

  3.  C-Shell

      o   comes with every unix system.

      o   is used by maybe 80% of the unix community.

      o   is  better for command-line input, since it provides a history
          mechanism,   and   has   a   simpler   (if    less    logical)
          control-structure  syntax,  which  improves  ease  of  command
          entry.

      o   is better than sh (history, alias etc.) in interactive use.

      o   for interactive use, history  was  nice  to  have,  but  csh's
          version is awkward to use.

      o   is  too  awkward  to program (compared to sh), and you have to
          make sure that any programs you write will really get executed
          by csh (the #!csh feature  is  HIGHLY  non-portable,  and  the
          conventions  for  using  csh  vs  sh  based on initial comment
          characters is also bogus.)

      o   The job control features which people often associate with csh
          are really operating-system based; csh has hooks for them  and
          sh doesn't.  Ksh does, so you can still use them.

      o   There  are  a  number of bugs in csh, and a number of very bad
          design choices, which make it unsuitable for programming.

      o   For programming most people recommend sh over csh

      o   If you plan to do any serious shell programming, you will come
          to loathe "csh" due to a questionable decision made early  on:
          it  does  not  fully parse its control structures, which means
          that things like nested "if" statements don't work right.

      o   University of Warwick (UK) give everybody /bin/csh by default,  but
          make it  plain that if they want it changed, it will be.

      o   shows its age.

  4.  Bash

      o   Bash  is  basically a reimplementation of ksh (with some other
          stuff thrown in as well).

      o   Its command syntax  if  the  same  as  the  Bourne  shell.  If
          anything at all is is a super-Bourne shell.

      o   bash  is usually obtained from public-domain-software sources.
          It offers, as its largest gain  over  sh  and  csh,  automatic
          command  and  filename completion.  Its control structures are
          also supposed to be augmented, and it pays attention to a more
          diverse   set   of   user-settable   environment-configuration
          variables.

      o   used mostly by people who want the  few  additions  and  don't
          have ksh.

      o   has  effective  interactive  functionality, and sh scripts are
          upward compatible to it.

      o   combines the good things in csh  (like ~/ instead  of  $HOME/,
          good  job  control,  etc) while allowing you to do programming
          stuff with the power of sh.

      o   has almost book-length buglists.

      o   I have heard that bash is buggy, but haven't noticed.

      o   Bash keystrokes are exactly the same  as  emacs.    So,  using
          emacs  and  bash,  you have only ONE set of keystrokes in your
          head.

      o   in the absence of 'ksh' use  'bash' or 'csh' in that order.

      o   With the next release of  GNU's bash it may come out ahead  of
          ksh, right now there are just too many little problems running
          it under SysV.

      o   When  Bash  1.06  comes  out, University of Bath plan to offer
          that as the standard shell.

      o   When the GNU shell, bash, stabilizes a bit more, this will  be
          worth  a  good look.   It is Bourne/Korn shell compatible, and
          has lots of nice features.  I currently have it up,  and  will
          set people's shell to it if they ask me, but I really  do  not
          consider it  solid  enough to use as a login shell, and don't
          advertise it.  I expect the next release to be a lot better, and
          I would guess that will be available about Christmas time.

      o   if you don't have ksh (or can't afford it)  I  recommend  bash
          from GNU, which has most of the same features, but seems to be
          slower.

      o   In  the process of considering we just had to make sure it was
          portable to all of our platforms, and it was  (with  a  little
          effort,   though).      So,   it  can  be  ported  to:  Apollo
          (3000+4000+10000), HP (300+400+800),  Tektronix  (88000),  Sun
          (Sp1).

  5.  Tcsh

      o   is  usually  obtained from public-domain-software sources...

      o   used mostly by people who want the  few  additions  and  don't
          have ksh.

      o   a hacked up version of csh with command line editing.

      o   I don't give this as standard because

          a.  it  isn't  standard,  so  if  people  get  used to it here
              they'll be confused when they go elsewhere
          b.  tcsh uses the emacs editing  set  whereas  our  most  used
              editor doesn't (although this is changing).

      o   We use tcsh at the moment, it is a modified csh which supports
          command line editing and retrieval in a similar manner to VMS.
          We  view  this  as  a temporary measure until V.4 arrives with
          ksh. I understand the ksh also supports these features.

      o   Definitely and  without  question,  you  should  go  for  tcsh
          (pronounced  tee-shell).    This  is an extension of csh, i.e.
          all csh syntax works for it, but additionally it has  a  bunch
          of features that are extremely useful and friendly.
          Most important is the command  line editing mechanism - if you
          make  a  typo in a command line which generates an  error, you
          can type "up-arrow" and it brings back the  erroneous  command
          line,  at  which  point  you  can edit that line interactively
          (using emacs syntax commands) and hit [RETURN] to execute  the
          corrected  command.    This  can  save  you  a  LOT of typing,
          especially for long and intricate commands

      o   Another  very  useful  function  in  tcsh  is   command   line
          completion.

  6.  expect

      o   is a shell intended primarily to control interactive programs.
          Using  expect,  you  can  program things that can only be done
          interactively with other shells.  For example, running telnet,
          passwd, su, tip, etc, doing job control, etc.

  7.  BRL's sh

      o   This includes interactive support features  the  equal  of  or
          superior  to  those  in  other  known shells (including tcsh),
          while avoiding the design mistakes of shells  like  "csh"  and
          "ksh".  At some time in the future I'll be upgrading our shell
          to SVR3.2 or SVR4 compatibility; meanwhile the SVR2 version is
          heavily used here.

  8.  Perl

      o   perl  which combines features from sh, C, awk and sed. I means
          that you don't have to get into awk and sed  as  soon  as  you
          want  to  do any text manipulation.  Its written by Larry Wall
          (who wrote patch) and has its own news group

  9.  msh

      o   is also a Bourne shell derivative, with screen based  editing,
          job  control  etc.  Most  people at the University of Bath (UK)
          use either 'sh', cos thats what they get given, or msh.

--
Alan Thew
University of Liverpool Computer Laboratory
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