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Full Discussion: to check if file is empty or not and return a non zero value
Top Forums UNIX for Dummies Questions & Answers to check if file is empty or not and return a non zero value Post 302260929 by jim mcnamara on Saturday 22nd of November 2008 08:45:38 AM
Old 11-22-2008
The shell does it - normal return values are: zero == true anything else == false

Code:
#one way
if [[ -s filename ]] ; then
      echo "filename exists and is > 0 bytes"
else
      echo "filename does not exist or is zero length"
fi
# another way
if [[ -f filename ]] ; then
      if [[ -s filename ]] ; then
             echo "filename exists and is > zero"
      else
             echo "filename exists and == zero "
      fi
else
      echo "filename does not exist"
fi

 

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LEARN ABOUT XFREE86

kstat

kstat(1M)						  System Administration Commands						 kstat(1M)

NAME

       kstat - display kernel statistics

SYNOPSIS

       kstat [-lpq] [-T  u | d ] [-c class] [-m module] [-i instance] [-n name] [-s statistic] [interval  [count]]

       kstat [-lpq] [-T  u | d ] [-c class] [module:instance:name:statistic...] [interval  [count]]

DESCRIPTION

       The  kstat utility examines the available kernel statistics, or kstats, on the system and reports those statistics which match the criteria
       specified on the command line. Each matching statistic is printed with its module, instance, and name fields, as well as its actual value.

       Kernel statistics may be published by various kernel subsystems, such as drivers or loadable modules; each kstat has a  module  field  that
       denotes	its  publisher. Since each module may have countable entities (such as multiple disks associated with the sd(7D) driver) for which
       it wishes to report statistics, the kstat also has an instance field to index the statistics for each entity; kstat instances are  numbered
       starting from zero. Finally, the kstat is given a name unique within its module.

       Each  kstat  may be a special kstat type, an array of name-value pairs, or raw data. In the name-value case, each reported value is given a
       label, which we refer to as the statistic. Known raw and special kstats are given statistic labels for each of their values by kstat; thus,
       all published values can be referenced as module:instance:name:statistic.

       When  invoked  without  any module operands or options, kstat will match all defined statistics on the system. Example invocations are pro-
       vided below.  All times are displayed as fractional seconds since system boot.

OPTIONS

       The tests specified by the following options are logically ANDed, and all matching kstats will be selected. A regular expression containing
       shell metacharacters must be protected from the shell by enclosing it with the appropriate quotes.

       The  argument for the -c, -i, -m, -n, and -s options may be specified as a shell glob pattern, or a Perl regular expression enclosed in '/'
       characters.

       -c class        Displays only kstats that match the specified class. class is a kernel-defined string which classifies the  "type"  of  the
		       kstat.

       -i instance     Displays only kstats that match the specified instance.

       -l	       Lists matching kstat names without displaying values.

       -m module       Displays only kstats that match the specified module.

       -n name	       Displays only kstats that match the specified name.

       -p	       Displays  output  in  parseable	format. All example output in this document is given in this format. If this option is not
		       specified, kstat produces output in a human-readable, table format.

       -q	       Displays no output, but return appropriate exit status for matches against given criteria.

       -s statistic    Displays only kstats that match the specified statistic.

       -T d | u        Displays a time stamp before each statistics block, either in ctime(3C) format ('d') or as an  alphanumeric  representation
		       of the value returned by time(2) ('u').

OPERANDS

       The following operands are supported:

       module:instance:name:statistic  Alternate  method  of specifying module, instance, name, and statistic as described above. Each of the mod-
				       ule, instance, name, or statistic specifiers may be a shell glob  pattern  or  a  Perl  regular	expression
				       enclosed  by  '/' characters. It is possible to use both specifier types within a single operand. Leaving a
				       specifier empty is equivalent to using the '*' glob pattern for that specifier.

       interval 		       The number of seconds between reports.

       count			       The number of reports to be printed.

EXAMPLES

       In the following examples, all the command lines in a block produce the same output, as shown immediately below. The exact  statistics  and
       values will of course vary from machine to machine.

       Example 1: Using the kstat Command

       example$ kstat -p -m unix -i 0 -n system_misc -s 'avenrun*'
       example$ kstat -p -s 'avenrun*'
       example$ kstat -p 'unix:0:system_misc:avenrun*'
       example$ kstat -p ':::avenrun*'
       example$ kstat -p ':::/^avenrun_d+min$/'

       unix:0:system_misc:avenrun_15min        3
       unix:0:system_misc:avenrun_1min 4
       unix:0:system_misc:avenrun_5min 2

       Example 2: Using the kstat Command

       example$ kstat -p -m cpu_stat -s 'intr*'
       example$ kstat -p cpu_stat:::/^intr/

       cpu_stat:0:cpu_stat0:intr       29682330
       cpu_stat:0:cpu_stat0:intrblk    87
       cpu_stat:0:cpu_stat0:intrthread 15054222
       cpu_stat:1:cpu_stat1:intr       426073
       cpu_stat:1:cpu_stat1:intrblk    51
       cpu_stat:1:cpu_stat1:intrthread 289668
       cpu_stat:2:cpu_stat2:intr       134160
       cpu_stat:2:cpu_stat2:intrblk    0
       cpu_stat:2:cpu_stat2:intrthread 131
       cpu_stat:3:cpu_stat3:intr       196566
       cpu_stat:3:cpu_stat3:intrblk    30
       cpu_stat:3:cpu_stat3:intrthread 59626

       Example 3: Using the kstat Command

       example$ kstat -p :::state ':::avenrun*'
       example$ kstat -p :::state :::/^avenrun/

       cpu_info:0:cpu_info0:state      on-line
       cpu_info:1:cpu_info1:state      on-line
       cpu_info:2:cpu_info2:state      on-line
       cpu_info:3:cpu_info3:state      on-line
       unix:0:system_misc:avenrun_15min        4
       unix:0:system_misc:avenrun_1min 10
       unix:0:system_misc:avenrun_5min 3

       Example 4: Using the kstat Command

       example$ kstat -p 'unix:0:system_misc:avenrun*' 1 3
       unix:0:system_misc:avenrun_15min        15
       unix:0:system_misc:avenrun_1min 11
       unix:0:system_misc:avenrun_5min 21

       unix:0:system_misc:avenrun_15min        15
       unix:0:system_misc:avenrun_1min 11
       unix:0:system_misc:avenrun_5min 21

       unix:0:system_misc:avenrun_15min        15
       unix:0:system_misc:avenrun_1min 11
       unix:0:system_misc:avenrun_5min 21

       Example 5: Using the kstat Command

       example$ kstat -p -T d 'unix:0:system_misc:avenrun*' 5 2
       Thu Jul 22 19:39:50 1999
       unix:0:system_misc:avenrun_15min        12
       unix:0:system_misc:avenrun_1min 0
       unix:0:system_misc:avenrun_5min 11

       Thu Jul 22 19:39:55 1999
       unix:0:system_misc:avenrun_15min        12
       unix:0:system_misc:avenrun_1min 0
       unix:0:system_misc:avenrun_5min 11

       Example 6: Using the kstat Command

       example$ kstat -p -T u 'unix:0:system_misc:avenrun*'
       932668656
       unix:0:system_misc:avenrun_15min        14
       unix:0:system_misc:avenrun_1min 5
       unix:0:system_misc:avenrun_5min 18

EXIT STATUS

       The following exit values are returned:

       0	One or more statistics were matched.

       1	No statistics were matched.

       2	Invalid command line options were specified.

       3	A fatal error occurred.

FILES

       /dev/kstat	       kernel statistics driver

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |ATTRIBUTE TYPE		     |ATTRIBUTE VALUE		   |
       +-----------------------------+-----------------------------+
       |Availability		     |SUNWcsu			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       sh(1), time(2), ctime(3C)gmatch(3GEN), kstat(3KSTAT), attributes(5), kstat(7D), sd(7D), kstat(9S)

NOTES

       If  the	pattern  argument contains glob or Perl RE metacharacters which are also shell metacharacters, it will be necessary to enclose the
       pattern with appropriate shell quotes.

SunOS 5.10							    14 Oct 2004 							 kstat(1M)
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