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Full Discussion: How to compare previous and current item in for loop in bash?
Top Forums Shell Programming and Scripting How to compare previous and current item in for loop in bash? Post 302988617 by kshji on Thursday 29th of December 2016 02:05:31 PM
Old 12-29-2016
Here is example to calculate diff between login and session time ... easy to modify ..
using ksh93
Code:
#!/usr/bin/ksh
prev=""
name="someuser"

for logu in /tmp/$lognam/wtmp*
do
  last -f "$logu" -F "$name"
done  | while read line
do
 flds=($line)
        loginstart="${flds[4]} ${flds[5]} ${flds[6]} ${flds[7]}"
        loginend="${flds[10]} ${flds[11]} ${flds[12]} ${flds[13]}"
        [ "$loginstart" = "" ] && continue
        [ "$prev" = "" ] && prev="$loginstart" && continue
        epocnow=$(printf "%(%#)T" "$loginstart")
        epoclogout=$(printf "%(%#)T" "$loginend")
        epocprev=$(printf "%(%#)T" "$prev")
        ((logintime=epoclogout - epocnow))
        ((diff=epocprev-epocnow))
        ((h=diff/3600))
        ((s1=diff-3600*h))
        ((m=s1/60))
        ((s=s1-m*60 ))
        echo "$diff|$logintime|$prev|$loginstart|$h:$m:$s"
        prev="$loginstart"
done

 

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LEARN ABOUT OSF1

wtmpconvert

wtmpconvert(8)						      System Manager's Manual						    wtmpconvert(8)

NAME

       wtmpconvert - Modify connect time accounting records from DIGITAL UNIX releases 4.0x and prior to new format

SYNOPSIS

       /usr/lbin/wtmpconvert [-vnrp?h] input_file [output_file]

OPTIONS

       Restore new format to old format.  Verbose. Display lines while converting.  Do not preserve contents of input file.  Formatted print only.
       Do not convert. (May be used with the -r option).  Display usage message.

DESCRIPTION

       The wtmpconvert command reads records from a connect time accounting file, such as /var/adm/wtmp, and converts the  record  format  to  the
       updated	struct	utmp  format.  If  no output file is specified or if the output file path is identical to the input file path, wtmpconvert
       makes a backup copy of the original input file using the following algorithm: If filename.orig exists.  Where n is a unique number.

       The wtmpconvert command attempts to detect an input file that is in the wrong format (for example, input  file  is  already  a  new  format
       file). A warning message is issued in this case, but conversion continues.

EXIT STATUS

       Success.  An error occurred.

EXAMPLES

       To convert an old format accounting file to the new format: wtmpconvert /var/adm/wtmp.prev

	      Upon  completion	of this command, /var/adm/wtmp.prev will have been converted to the new format. The original /var/adm/wtmp.prev is
	      renamed to /var/adm/wtmp.prev.orig.  To convert a wtmp  file  in	new  format  to  the  old  format:  wtmpconvert  -r  /var/adm/wtmp
	      /var/adm/wtmp.old

FILES

       Accounting header files that define the format for the login database file.  The active login/logoff database files.

SEE ALSO

       Commands: acct(8), acctcon(8), acctmerg(8), date(1), runacct(8)

       Functions: getutent(3)

       Files: utmp(4), wtmp(4)

																    wtmpconvert(8)
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