New Messages

From: Matthew Cheek (cheek@mars-system.com)
Subject: Aug 2000 article comment

I wish to comment on a statement in the article “Logical Volume Manager for Linux”, by Rafeeq Ur Rehman in the August 2000 issue of Sys Admin. In the second paragraph, Mr. Rehman states: “HP-UX and Digital UNIX use the OSF version of LVM, while Solaris uses Veritas.”

While a quick glance at the HP-UX Web site indicates that HP-UX 10 and 11 use an “OSF-defined Logical Volume Manager”, Digital UNIX (or rather, Compaq Tru64 UNIX) does not. The Tru64 UNIX logical volume manager is Logical Storage Manager (LSM) which is, in fact, an OEM'ed version of the Veritas Volume Manager (VM). In the Solaris environment, systems administrators have two logical volume manager choices: Solstice DiskSuite (SDS) and Veritas VM. Additionally, SDS and VM are not mutually exclusive and can co-exist on the same Solaris system. For example, I have administered Solaris systems where SDS is used to managed the boot disk(s), and VM is used to manage application and data volumes. Finally, while the HP-UX LVM is tightly integrated into the operating system (i.e., you can't not use it), logical volume managers are currently optional (and sometime extra cost) add-on products for Compaq Tru64 UNIX, Sun Solaris, and Linux.

Other than this very minor error, this article proved to be a very well presented introduction to the Linux LVM.

Matthew Cheek
Sr. UNIX System Administrator
Medical Archival Systems, Inc.

Matthew,
To the best of my knowledge the OSF version served as base for original digital UNIX LVM. However different names were adopted by different companies. This is also mentioned on Linux LVM Web page: http://linux.msede.com/lvm/. I am not sure about the OEM version used by Compaq.

Rafeeq Ur Rehman

From: Dan Singer (des@cs.duke.edu)
Subject: Your article on cmdline-options

Ed-
I enjoyed your article “Processing Command-Line Options in the Shell”. I do a lot of shell scripting, and I never use getopts due to the limitations you mention and others. Usually, for most scripts, I just use a “while” loop, similar to your Listing #2. But when I want to get really fancy (like for a script that I'm going to tell a lot of people about), I use something like the code that's included in the attachment. It provides a lot of option processing flexibility, very similar to what you get with typical, compiled UNIX commands. It can also be easily modified for particular situations. If you don't already have some code like this laying around, I hope that you might find this useful.

Regards,
Dan

#!/bin/sh
# newopts: options handling code
#
# 8/97, D.Singer

PROG='basename $0'
USAGE="Usage: $PROG ..."
SYNTAX="_$PROG: option syntax error."

#
# platform specific settings
#
AWK="awk"
SYS="'uname -sr'"      # OS type
case "$SYS" in
  "SunOS "*)
AWK="nawk"
  esac

syntax_error() {
echo "$SYNTAX" >&2
echo "$USAGE" >&2
exit 1
}

arg_syntax_check() {
[ "$1" -lt 1 ] && syntax_error
}

while [ "$#" -gt 0 ]; do
OPT="$1"
case "$OPT" in
  # options without argument
  -a)
      AFLAG=1
      ;;
  # options with argument
  -c)
      shift
      arg_syntax_check "$#"
      CARG="$1"
      CFLAG=1
      ;;
  # ...
  # options with long names
  --long)
      LONG_FLAG=1
      ;;
  # ...
  # end of options
  --)
      shift
      break
      ;;
  --*)
      syntax_error
      ;;

        # unknown option
  -?)
      syntax_error
      ;;
  # compound option
  -??*)
      # break up a compound option
      NEW_OPTS='$AWK 'BEGIN {
          OPT_STR = "'"$OPT"'";
          LEN = length(OPT_STR);
          NEW_OPTS = "";
          STATUS = 0;
          for (POS=2; POS+0 <= LEN; ++POS) {
              OPT = substr(OPT_STR,POS,1);
              if (OPT !~ /[a-zA-Z0-9_]/)
                  STATUS = 1;
              NEW_OPTS = NEW_OPTS " -" OPT;
          }
          print NEW_OPTS;
          exit STATUS;
        }' <&-' || {
          syntax_error
        }
      shift
      set -- $NEW_OPTS ${1:+"$@"}
      continue
      ;;
  # end of options, just command arguments left
  *)
      break
  esac
shift
  done

#ARGV="$*"

From: Henk M. Keller (henk@ATComputing.nl)
Subject: Your article on cmdline-options

Dear Mr. Schaefer,
I read your article on processing command-line options in shell files in the July issue of Sys Admin. A good idea to pay attention to that subject!

I would like to make some remarks on the second script (option.sh):

1. As far as I can see, your script stumbles on a command line like:

   option.sh -PARM

because it will try to do two “shift”s with only one argument available.

2. You use the command cut to split -PARM and the value. This is an extra process. They are not really expensive, but using the Korn shell (or bash or zsh and the like) this can be done without an extra process:

   PARM=${1#-PARM}
   

   echo >&2 "$0: Illegal Command-line Option"
   exit 1

 1  #!/bin/ksh
 2  # Keyword parameter demo
 3  #       Accepts arguments like
 4  #               F1=value
 5  #               F1= value
 6  #               F1 =value
 7  #               F1 = value
 8  # (c) 2000 AT Computing, Henk Keller
 9  status=         # empty: nothing seen
10                  # p     up to parameter name seen
11                  # pe    up to equals sign seen
12                  # pev   up to value seen
13  while [ "$#" -gt 0 ]
14  do
15          case "$status$1" in
16          F1)
17                  status="p"
18                  shift
19                  ;;
20          F1=)
21                  status="pe"
22                  shift
23                  ;;
24          F1=*)
25                  status="pev"
26                  F1=${1#F1=}  # in sh: F1='expr "$1 : '...\(.*\)''
27                  shift
28                  ;;
29          pe*)
30                  status="pev"
31                  F1="${1}"
32                  shift
33                  ;;
34          p=)
35                  status="pe"
36                  shift
37                  ;;
38          p=*)
39                  status="pev"
40                  F1=${1#=}    # in sh: F1='expr $1 : '.\(.*\)''
41                  shift
42                  ;;
43          *)
44                  echo>&2 "$0: Unknown argument '$1'"
45                  exit 1
46          esac
47  done
48
49  case "${status}" in
50  p|pe)
51          echo>&2 "$0: missing value for F1"
52          exit 2
53          ;;
54  pev)
55          echo "$0: The value for F1 is '$F1'"
56          exit 0
57          ;;
58  esac