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Calculate datediff

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# 1  
Old 10-05-2017
Calculate datediff
I'm trying to calculate datediff between string from filename and current date,
i got problem with storing variable from date command

Code:
now=$(date  +"%s")
echo "NOW = ${now}";
file=$(ls -1Ap *.txt|grep -v /\$ |tail -1)
echo "file name is $file"
#filename 201710030549.txt

y=$(echo $file|cut -c 1-4)
m=$(echo $file|cut -c 5-6)
d=$(echo $file|cut -c 7-8)

in="$m/${d}/${y}"

$fdate=`$(date -d "$in" +"%s")`
echo "file date = $fdate"
echo $(( (now - fdate) / 86400 )) days

error result
Code:
NOW = 1507184947
file name is 201710050619.txt
./test.sh: line 14: 1507136400: command not found
./test.sh: line 14: =: command not found
file date = 
17444 days

# 2  
Old 10-05-2017
This is double command substitution (both ` ... ` and $( ... ) plus the first dollar sign should not be there:

Quote:
Originally Posted by before4
Code:
[..]
$fdate=`$(date -d "$in" +"%s")`
[..]

Try:
Code:
fdate=$(date -d "$in" +"%s")

Last edited by Scrutinizer; 10-05-2017 at 04:03 AM..
This User Gave Thanks to Scrutinizer For This Post:
before4
# 3  
Old 10-05-2017
From your usage of date I would guess that you are (1) using Gnu utilities and therefore (2) are on a Linux distro and therefore (3) using bash.

Try this:
Code:
now=$(date  +"%s")
echo "NOW = ${now}";
file=$(ls -1r *.txt|head -1)
echo "file name is $file"
#filename 201710030549.txt

fdate=$(date -d ${filename:0:8} +"%s")
echo "file date = $fdate"
echo $(( (now - fdate) / 86400 )) days

Adding -r to ls allows us to use head instead of tail. Also, it is unlikely that
there will be a directory with the .txt extension the the -p and the grep should not be needed. The -A is also useless in this context.

The variable expansion ${var:offset:len} will produce len characters from the offset position (starting from zero), so ${filename:0:8} will produce 20171003.

date will understand 20171003 as 3rd October 2017 so you don't need to chop up the date.

Hope this helps.

Andrew
This User Gave Thanks to apmcd47 For This Post:
before4
# 4  
Old 10-05-2017
Quote:
Originally Posted by apmcd47
From your usage of date I would guess that you are (1) using Gnu utilities and therefore (2) are on a Linux distro and therefore (3) using bash.

Try this:
Code:
now=$(date  +"%s")
echo "NOW = ${now}";
file=$(ls -1r *.txt|head -1)
echo "file name is $file"
#filename 201710030549.txt

fdate=$(date -d ${filename:0:8} +"%s")
echo "file date = $fdate"
echo $(( (now - fdate) / 86400 )) days

Adding -r to ls allows us to use head instead of tail. Also, it is unlikely that
there will be a directory with the .txt extension the the -p and the grep should not be needed. The -A is also useless in this context.

The variable expansion ${var:offset:len} will produce len characters from the offset position (starting from zero), so ${filename:0:8} will produce 20171003.

date will understand 20171003 as 3rd October 2017 so you don't need to chop up the date.

Hope this helps.

Andrew
Thanks, that much cleaner.
Code:
ow=$(date  +"%s")
echo "NOW = ${now}";
file=$(ls -1r *.txt|head -1)
echo "file name is $file"
#filename 201710030549.txt
echo ${file:0:8}
fdate=$(date -d ${file:0:8} +"%s")
echo "file date = $fdate"
echo $(( (now - fdate) / 86400 )) days
~

Code:
./test2.sh 
NOW = 1507195265
file name is 201710042019.txt
20171004
file date = 1507050000
1 days

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