a

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

			  in Special Commands below).

      The shell gives default values to PATH, PS1, PS2, MAILCHECK, TMOUT,
      and IFS.	HOME, SHELL, ENV, and MAIL are never set automatically by
      the shell (although HOME, SHELL, and MAIL are set by login(1)).

    Blank Interpretation
      After parameter and command substitution, the results of substitution
      are scanned for field separator characters (found in IFS), and split
      into distinct arguments where such characters are found.	ksh retains
      explicit null arguments ( or '') but removes implicit null arguments
      (those resulting from parameters that have no values).

    File Name Generation
      Following substitution, each command word is processed as a pattern
      for file name expansion unless the -f option has been set.  The form
      of the patterns is the Pattern Matching Notation defined by regexp(5).
      The word is replaced with sorted file names matching the pattern.	 If
      no file name is found that matches the pattern, the word is left
      unchanged.

      In addition to the notation described in regexp(5), ksh recognizes
      composite patterns made up of one or more pattern lists separated from
      each other with a |.  Composite patterns can be formed with one or
      more of the following:

	   ?(pattern-list)     Optionally matches any one of the given
			       patterns.

	   *(pattern-list)     Matches zero or more occurrences of the given
			       patterns.

	   +(pattern-list)     Matches one or more occurrences of the given
			       patterns.

	   @(pattern-list)     Matches exactly one of the given patterns.

	   !(pattern-list)     Matches anything, except one of the given
			       patterns.

    Quoting
      Each of the metacharacters listed above (See Definitions above) has a
      special meaning to the shell and causes termination of a word unless
      quoted.  A character can be quoted (i.e., made to stand for itself) by
      preceding it with a \.  The pair \new-line is ignored.  All characters
      enclosed between a pair of single quote marks (''), are quoted.  A
      single quote cannot appear within single quotes.	Inside double quote
      marks (""), parameter and command substitution occurs and \ quotes the
      characters \, `, ", and $.  $* and $@ have identical meanings when not
      quoted or when used as a parameter assignment value or as a file name.
      However, when used as a command argument, "$*" is equivalent to



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      "$1d$2d...", where d is the first character of the IFS parameter,
      whereas "$@" is equivalent to "$1" "$2" ....  Inside back single quote
      (accent grave) marks (``) \ quotes the characters \, `, and $.  If the
      back single quotes occur within double quotes, \ also quotes the
      character ".

      The special meaning of keywords or aliases can be removed by quoting
      any character of the keyword.  The recognition of function names or
      special command names listed below cannot be altered by quoting them.

    Arithmetic Evaluation
      The ability to perform integer arithmetic is provided with the special
      command let.  Evaluations are performed using long arithmetic.
      Constants take the form [base#]n, where base is a decimal number
      between two and thirty-six representing the arithmetic base and n is a
      number in that base.  If base is omitted, base 10 is used.

      An arithmetic expression uses the same syntax, precedence, and
      associativity of expression of the C language.  All the integral
      operators, other than ++, --, ?:, and , are supported.  Variables can
      be referenced by name within an arithmetic expression without using
      the parameter substitution syntax.  When a variable is referenced, its
      value is evaluated as an arithmetic expression.

      An internal integer representation of a variable can be specified with
      the -i option of the typeset special command.  Arithmetic evaluation
      is performed on the value of each assignment to a variable with the -i
      attribute.  If you do not specify an arithmetic base, the first
      assignment to the variable determines the arithmetic base.  This base
      is used when parameter substitution occurs.

      Since many of the arithmetic operators require quoting, an alternative
      form of the let command is provided.  For any command beginning with
      ((, all characters until the matching )) are treated as a quoted
      expression.  More precisely, ((...)) is equivalent to let "...".

    Prompting
      When used interactively, the shell prompts with the value of PS1
      before reading a command.	 If at any time a new-line is typed and
      further input is needed to complete a command, the secondary prompt
      (the value of PS2) is issued.

    Conditional Expressions.
      A conditional expression is used with the [[ compound command to test
      attributes of files and to compare strings.  Word splitting and file
      name generation are not performed on the words between [[ and ]].
      Each expression can be constructed from one or more of the following
      unary or binary expressions:

	   -a file	       True if file exists.




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	   -b file	       True if file exists and is a block special
			       file.
	   -c file	       True if file exists and is a character
			       special file.
	   -d file	       True if file exists and is a directory.
	   -f file	       True if file exists and is an ordinary file.
	   -g file	       True if file exists and is has its setgid bit
			       set.
	   -h file	       True if file exists and is a a symbolic link.
	   -k file	       True if file exists and is has its sticky bit
			       set.
	   -n string	       True if length of string is non-zero.
	   -o option	       True if option named option is on.
	   -p file	       True if file exists and is a fifo special
			       file or a pipe.
	   -r file	       True if file exists and is readable by
			       current process.
	   -s file	       True if file exists and has size greater than
			       zero.
	   -t fildes	       True if file descriptor number fildes is open
			       and associated with a terminal device.
	   -u file	       True if file exists and is has its setuid bit
			       set.
	   -w file	       True if file exists and is writable by
			       current process.
	   -x file	       True if file exists and is executable by
			       current process.	 If file exists and is a
			       directory, the current process has permission
			       to search in the directory.
	   -z string	       True if length of string is zero.
	   -L file	       True if file exists and is a symbolic link.
	   -O file	       True if file exists and is owned by the
			       effective user ID of this process.
	   -G file	       True if file exists and its group matches the
			       effective group ID of this process.
	   -S file	       True if file exists and is a socket.
	   file1 -nt file2     True if file1 exists and is newer than file2.
	   file1 -ot file2     True if file1 exists and is older than file2.
	   file1 -ef file2     True if file1 and file2 exist and refer to
			       the same file.
	   string = pattern    True if string matches pattern.
	   string != pattern   True if string does not match pattern.
	   string1 < string2   True if string1 comes before string2 based on
			       ASCII value of their characters.
	   string1 > string2   True if string1 comes after string2 based on
			       ASCII value of their characters.
	   exp1 -eq exp2       True if exp1 is equal to exp2.
	   exp1 -ne exp2       True if exp1 is not equal to exp2.
	   exp1 -lt exp2       True if exp1 is less than exp2.
	   exp1 -gt exp2       True if exp1 is greater than exp2.




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	   exp1 -le exp2       True if exp1 is less than or equal to exp2.
	   exp1 -ge exp2       True if exp1 is greater than or equal to
			       exp2.

      A compound expression can be constructed from these primitives by
      using any of the following, listed in decreasing order of precedence.

	   (expression)			      True, if expression is true.
					      Used to group expressions.
	   ! expression			      True if expression is false.
	   expression1 && expression2	      True, if expression1 and
					      expression2 are both true.
	   expression1 || expression2	      True, if either expression1 or
					      expression2 is true.

    Input/Output
      Before a command is executed, its input and output can be redirected
      using a special notation interpreted by the shell.  The following can
      appear anywhere in a simple-command or can precede or follow a command
      and are not passed on to the invoked command.  Command and parameter
      substitution occurs before word or digit is used, except as noted
      below.  File name generation occurs only if the pattern matches a
      single file and blank interpretation is not performed.

	   <word	  Use file word as standard input (file descriptor
			  0).

	   >word	  Use file word as standard output (file descriptor
			  1).  If the file does not exist, it is created.
			  If the file exists, and the noclobber option is
			  on, an error occurs; otherwise, the file is
			  truncated to zero length.

	   >|word	  Sames as >, except that it overrides the noclobber
			  option.

	   >>word	  Use file word as standard output.  If the file
			  exists, output is appended to it (by first
			  searching for the end-of-file); otherwise, the
			  file is created.

	   <>word	  Open file word for reading and writing as standard
			  input.  If the file does not exist it is created.

	   <<[-]word	  The shell input is read up to a line that matches
			  word, or to an end-of-file.  No parameter
			  substitution, command substitution, or file name
			  generation is performed on word.  The resulting
			  document, called a here-document, becomes the
			  standard input.  If any character of word is
			  quoted, no interpretation is placed upon the



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			  characters of the document.  Otherwise, parameter
			  and command substitution occurs, \new-line is
			  ignored, and \ must be used to quote the
			  characters \, $, `, and the first character of
			  word.	 If - is appended to <<, all leading tabs
			  are stripped from word and from the document.

	   <&digit	  The standard input is duplicated from file
			  descriptor digit (see dup(2)).

	   >&digit	  The standard output is duplicated to file
			  descriptor digit (see dup(2)).

	   <&-		  The standard input is closed.

	   >&-		  The standard output is closed.

	   <&p		  The input from the co-process is moved to standard
			  input.

	   >&p		  The output to the co-process is moved to standard
			  output.

      If one of the above is preceded by a digit, the file descriptor number
      cited is that specified by the digit (instead of the default 0 or 1).
      For example:

	   ... 2>&1

      means file descriptor 2 is to be opened for writing as a duplicate of
      file descriptor 1.

      Redirection order is significant because the shell evaluates
      redirections referencing file descriptors in terms of the currently
      open file associated with the specified file descriptor at the time of
      evaluation.  For example:

	   ...	1>fname 2>&1

      first assigns file descriptor 1 (standard output) to file	 fname ,
      then assigns file descriptor 2 (standard error) to the file assigned
      to file descriptor 1; i.e., fname.  On the other hand, if the order of
      redirection is reversed as follows:

	   ...	2>&1 1>fname

      file descriptor 2 is assigned to the current standard output (user
      terminal unless a different assignment is inherited).  File descriptor
      1 is then reassigned to file fname without changing the assignment of
      file descriptor 2.




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      The input and output of a co-process can be moved to a numbered file
      descriptor allowing other commands to write to them and read from them
      using the above redirection operators.  If the input of the current
      co-process is moved to a numbered file descriptor, another co-process