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Full Discussion: Trap explanation?
Top Forums UNIX for Beginners Questions & Answers Trap explanation? Post 303004477 by SIMMS7400 on Tuesday 3rd of October 2017 06:56:23 AM
Old 10-03-2017
Trap explanation?

Hi Folks -

Could someone help me understand something about my trap statement? I've been using the following trap statement for a while now and its works perfectly. The first part of the shell scripts look like such:

Code:
source "/home/EPMTrain1/Hyperion_Batch/Scripts/Batch/_env.sh"

#::-- Set Log & Error subdirectories pertaining to the specific process --::#
_PLOGPATH=Auto_Train_Logs/
_PERRORPATH=Auto_Train_Errors/

#::-- Establish STDOUT and STDERROR repositories --::
_INTRAPATH=${_LOGPATH}${_PLOGPATH}${_YEAR}_${_MONTH}${_DAY}
_ERRORINTRAPATH=${_ERRORPATH}${_PERRORPATH}${_YEAR}_${_MONTH}${_DAY}
    
mkdir -p "${_INTRAPATH}"
mkdir -p "${_ERRORINTRAPATH}"

#::-- Prepare File Name Format --::#
#::   _SN          = Script Name with extension
#::   ${_SN%%.sh*} = Script name without extension
#::   _FN          = File Name

_SN=${0##*/}
_FN=${_DATESTAMP}_${_TIME}_${_SN%%.sh*}

#::-- Establish STDOUT and STDERROR files --::#
_LOGFILE=${_INTRAPATH}/${_FN}.log
_ERRORFILE=${_ERRORINTRAPATH}/${_FN}.err
_MAXLLOGFILE=${_INTRAPATH}/${_FN}_MAXL.log

#::-- Direct STDOUT and STDERROR to repositories --::# 
exec 2>"${_ERRORFILE}" > "${_LOGFILE}"

#::-- If empty, delete YYYY_MMDD error file subdirectory --::
trap "[ -s ${_ERRORFILE} ] || rm -f ${_ERRORFILE} && rmdir ${_ERRORINTRAPATH}" EXIT

My question is, in the trap argument, if ${_ERRORFILE} doesn't exist, it will proceed to the next command in the argument. but if it doesn't exist, why would I need to "remove it" again? Obviously it will always result in a "0" of that command since I"m forcing it (and thus, will proceed due to &&) but I'm just curious.

Perhaps someone can explain it so it makes more sense to me? Thanks!

Last edited by rbatte1; 10-03-2017 at 09:34 AM..
 

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