I am trying to figure out what this script does. Can someone help?
Code:
delt_file=`diff /transfer/adx/tey_header.txt /transfer/adx/tey_header_yesterdy.txt`
if [[ $delt_file == "" ]] ; then
touch /transfer/adx/lrstb028_ctl2.ctl
else
if test -f "/transfer/adx/lrstb028_ctl2_2.ctl" ; then
touch /transfer/adx/lrstb028_ctl2.ctl
fi
fi
Last edited by Scott; 09-17-2010 at 05:04 PM..
Reason: Added CODE tags, removed formatting
Compares tey_header.txt to tey_header_yesterday.txt. If there's any differences between them, diff will output text describing it. If not, there will be no output. Because of the backticks, the output is saved into the variable delt_file.
I don't see that they actually use the output they saved here, but this may not be the whole script, yes?
Code:
if [[ $delt_file == "" ]] ; then
touch /transfer/adx/lrstb028_ctl2.ctl
else
if test -f "/transfer/adx/lrstb028_ctl2_2.ctl" ; then
touch /transfer/adx/lrstb028_ctl2.ctl
fi
fi
If delt_file is empty -- as in, no changes -- update the timestamp on /transfer/adx/lrstb028_ctl2.ctl to today. That's what touch does, alters the timestamp without otherwise altering the file.
If delt_file is not empty, and /transfer/adx/lrstb028_ctl2_2.ctl exists, update its timestamp instead.
I'd rewrite it a little as:
Code:
delt_file=`diff /transfer/adx/tey_header.txt /transfer/adx/tey_header_yesterdy.txt`
if [[ "$delt_file" == "" ]] ; then
touch /transfer/adx/lrstb028_ctl2.ctl
else
[ -f "/transfer/adx/lrstb028_ctl2_2.ctl" ] && touch /transfer/adx/lrstb028_ctl2.ctl
fi
...still keeps the output in delt_file in case they need it, but doesn't potentially break if its output contains spaces or newlines, and doesn't need to nest two if statements inside each other.
And if they don't even use diff's output anywhere this can boil down to
Code:
# Check if the files differ. Will return success on no change, error on change.
if diff /transfer/adx/tey_header.txt /transfer/adx/tey_header_yesterdy.txt > /dev/null
then
# No change. Update the timestamp on lrstb028_ctl2.ctl.
touch /transfer/adx/lrstb028_ctl2.ctl
# The files differ. Does /transfer/adx/lrstb028_ctl2_2.ctl exist?
elif [ -f "/transfer/adx/lrstb028_ctl2_2.ctl" ]
then
# Update the timestamp on /transfer/adx/lrstb028_ctl2.ctl
touch /transfer/adx/lrstb028_ctl2.ctl
fi
Last edited by Corona688; 09-17-2010 at 06:28 PM..
think using shift would help me finish my script but cant get it work without your help. would appreciate if you give me a example with shift & counter in the same script so I can later work on that to my one.
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