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ksh 实现的基于hpux下的性能数据以及故障的采集程序。可以作为新手练手使用

    Parameter Substitution
      A parameter is an identifier, one or more digits, or any of the
      characters *, @, #, ?, -, $, and !.  A named parameter (a parameter
      denoted by an identifier) has a value and zero or more attributes.
      Named parameters can be assigned values and attributes by using the
      typeset special command.	Attributes supported by ksh are described
      later with the typeset special command.  Exported parameters pass
      values and attributes to the environment.

      The shell supports a limited one-dimensional array facility.  An
      element of an array parameter is referenced by a subscript.  A
      subscript is denoted by a [ followed by an arithmetic expression (see
      Arithmetic Evaluation below) followed by a ].  To assign values to an
      array, use set -A name value ....	 The value of all subscripts must be
      in the range of 0 through 1023.  Arrays need not be declared.  Any
      reference to a named parameter with a valid subscript is legal and an
      array is created if necessary.  Referencing an array without a
      subscript is equivalent to referencing the first element.

      The value of a named parameter can also be assigned by writing:

	   name=value [name=value] ...

      If the -i integer attribute is set for name, the value is subject to
      arithmetic evaluation as described below.

      Positional parameters, parameters denoted by a number, can be assigned
      values with the set special command.  Parameter $0 is set from
      argument zero when the shell is invoked.

      The character $ is used to introduce substitutable parameters.

	   ${parameter}	       Substitute the value of the parameter, if
			       any.  Braces are required when parameter is
			       followed by a letter, digit, or underscore
			       that should not be interpreted as part of its
			       name or when a named parameter is
			       subscripted.  If parameter is one or more
			       digits, it is a positional parameter.  A
			       positional parameter of more than one digit
			       must be enclosed in braces.  If parameter is
			       * or @ all the positional parameters,
			       starting with $1, are substituted (separated
			       by a field separator character).	 If an array
			       identifier with subscript * or @ is used, the
			       value for each element is substituted
			       (separated by a field separator character).
			       The shell reads all the characters from ${ to
			       the matching } as part of the same word even
			       if it contains braces or metacharacters.




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 ksh(1)								      ksh(1)




	   ${#parameter}       If parameter is * or @, the number of
			       positional parameters is substituted.
			       Otherwise, the length of the value of the
			       parameter is substituted.

	   ${#identifier[*]}   Substitute the number of elements in the
			       array identifier.

	   ${parameter:-word}  If parameter is set and is non-null,
			       substitute its value; otherwise substitute
			       word.

	   ${parameter:=word}  If parameter is not set or is null, set it to
			       word; then substitute the value of the
			       parameter.  Positional parameters cannot be
			       assigned in this way.

	   ${parameter:?word}  If parameter is set and is non-null,
			       substitute its value; otherwise, print word
			       and exit from the shell.	 If word is omitted,
			       a standard message is printed.

	   ${parameter:+word}  If parameter is set and is non-null,
			       substitute word; otherwise substitute
			       nothing.

	   ${parameter#pattern}
	   ${parameter##pattern}
			       If the shell pattern matches the beginning of
			       the value of parameter, the value of this
			       substitution is the value of the parameter
			       with the matched portion deleted; otherwise
			       the value of this parameter substituted.	 In
			       the former case, the smallest matching
			       pattern is deleted; in the latter case, the
			       largest matching pattern is deleted.

	   ${parameter%pattern}
	   ${parameter%%pattern}
			       If the shell pattern matches the end of the
			       value of parameter, the value of parameter
			       with the matched part is deleted; otherwise
			       substitute the value of parameter.  In the
			       former, the smallest matching pattern is
			       deleted; in the latter, the largest matching
			       pattern is deleted.

	   In the above, word is not evaluated unless it is used as the
	   substituted string.	Thus, in the following example, pwd is
	   executed only if d is not set or is null:




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 ksh(1)								      ksh(1)




		echo ${d:-$(pwd)}

	   If the colon (:) is omitted from the above expressions, the shell
	   only checks to determine whether or not parameter is set.

      The following parameters are set automatically by the shell:

	   #		  The number of positional parameters in decimal.
	   -		  Options supplied to the shell on invocation or by
			  the set command.
	   ?		  The decimal value returned by the last executed
			  command.
	   $		  The process number of this shell.
	   _		  Initially, the value of _ is an absolute pathname
			  of the shell or script being executed as passed in
			  the environment.  Subsequently it is assigned the
			  last argument of the previous command.  This
			  parameter is not set for commands which are
			  asynchronous.	 This parameter is also used to hold
			  the name of the matching MAIL file when checking
			  for mail.
	   !		  The process number of the last background command
			  invoked.
	   COLUMNS	  If this variable is set, its value is used to
			  define the width of the edit window for the shell
			  edit modes and for printing select lists.  In a
			  windowed environment, if the shell detects that
			  the window size has changed, the shell updates the
			  value of COLUMNS.
	   ERRNO	  The value of errno as set by the most recently
			  failed system call.  This value is system
			  dependent and is intended for debugging purposes.
	   LINENO	  The line number of the current line within the
			  script or function being executed.
	   LINES	  If this variable is set, the value is used to
			  determine the column length for printing select
			  lists.  select lists print vertically until about
			  two-thirds of LINES lines are filled.	 In a
			  windowed environment, if the shell detects that
			  the window size has changed, the shell updates the
			  value of LINES.
	   OLDPWD	  The previous working directory set by the cd
			  command.
	   OPTARG	  The value of the last option argument processed by
			  the getopts special command.
	   OPTIND	  The index of the last option argument processed by
			  the getopts special command.
	   PPID		  The process number of the parent of the shell.
	   PWD		  The present working directory set by the cd
			  command.




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 ksh(1)								      ksh(1)




	   RANDOM	  Each time this parameter is evaluated, a random
			  integer, uniformly distributed between 0 and
			  32767, is generated.	The sequence of random
			  numbers can be initialized by assigning a numeric
			  value to RANDOM.
	   REPLY	  This parameter is set by the select statement and
			  by the read special command when no arguments are
			  supplied.
	   SECONDS	  Each time this parameter is referenced, the number
			  of seconds since shell invocation is returned.  If
			  this parameter is assigned a value, the value
			  returned upon reference is the value that was
			  assigned plus the number of seconds since the
			  assignment.

      The following parameters are used by the shell:

	   CDPATH	  The search path for the cd command.
	   EDITOR	  If the value of this variable ends in emacs,
			  gmacs, or vi and the VISUAL variable is not set,
			  the corresponding option is turned on (see set in
			  Special Commands below).
	   ENV		  If this parameter is set, parameter substitution
			  is performed on the value to generate the path
			  name of the script to be executed when the shell
			  is invoked (see Invoking ksh below).	This file is
			  typically used for alias and function definitions.
	   FCEDIT	  The default editor name for the fc command.
	   FPATH	  The search path for function definitions.  This
			  path is searched when a function with the -u
			  attribute is referenced and when a command is not
			  found.  If an executable file is found, then it is
			  read and executed in the current environment.
	   IFS		  Internal field separators, normally space, tab,
			  and new-line that are used to separate command
			  words resulting from command or parameter
			  substitution, and for separating words with the
			  special command read.	 The first character of the
			  IFS parameter is used to separate arguments for
			  the "$*" substitution (see Quoting below).
	   HISTFILE	  If this parameter is set when the shell is
			  invoked, its value is the path name of the file
			  that is used to store the command history.  The
			  default value is $HOME/.sh_history.  If the user
			  has appropriate privileges and no HISTFILE is
			  given, then no history file is used (see Command
			  Re-entry below).
	   HISTSIZE	  If this parameter is set when the shell is
			  invoked, the number of previously entered commands
			  accessible to this shell will be greater than or
			  equal to this number.	 The default is 128.



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	   HOME		  The default argument (home directory) for the cd
			  command.
	   MAIL		  If this parameter is set to the name of a mail
			  file and the MAILPATH parameter is not set, the
			  shell informs the user of arrival of mail in the
			  specified file.
	   MAILCHECK	  This variable specifies how often (in seconds) the
			  shell checks for changes in the modification time
			  of any of the files specified by the MAILPATH or
			  MAIL parameters.  The default value is 600
			  seconds.  When the time has elapsed the shell
			  checks before issuing the next prompt.
	   MAILPATH	  A list of file names separated by colons (:).	 If
			  this parameter is set, the shell informs the user
			  of any modifications to the specified files that
			  have occurred within the last MAILCHECK seconds.
			  Each file name can be followed by a ? and a
			  message to be printed, in which case the message
			  undergoes parameter and command substitution with
			  the parameter $_ defined as the name of the
			  changed file.	 The default message is you have
			  mail in $_.
	   PATH		  The search path for commands (see Execution
			  below).  The user cannot change PATH if executing
			  rksh (except in the .profile file).
	   PS1		  The value of this parameter is expanded for
			  parameter substitution, to define the primary
			  prompt string which, by default, is $ followed by
			  a space character.  The character ! in the primary
			  prompt string is replaced by the command number
			  (see Command Re-entry below).	 To include a ! in
			  the prompt, use !!.
	   PS2		  Secondary prompt string, by default > followed by
			  a space character.
	   PS3		  Selection prompt string used within a select loop,
			  by default #? followed by a space character.
	   PS4		  The value of this variable is expanded for
			  parameter substitution and precedes each line of
			  an execution trace.  If PS4 is unset, the
			  execution trace prompt is + followed by a space
			  character.
	   SHELL	  The path name of the shell is kept in the
			  environment.	When invoked, the shell is
			  restricted if the value of this variable contains
			  an r in the basename.
	   TMOUT	  If set to a value greater than zero, the shell
			  terminates if a command is not entered within the
			  prescribed number of seconds after issuing the PS1
			  prompt.
	   VISUAL	  Invokes the corresponding option when the value of
			  this variable ends in emacs, gmacs, or vi (see set



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 ksh(1)								      ksh(1)