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Odd and even date in bash

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Top Forums Shell Programming and Scripting Odd and even date in bash
# 1  
Old 11-08-2013
Odd and even date in bash
Hi All,

I'm having the following script:

Code:
#!/bin/bash

date=$(date +%d)

echo $date

if [ ${date%2} -eq 0 ];

then

echo 'date is even'

else

echo 'date is odd'

fi

but I can not find out why it's not working.Example:

Code:
cat test_even.sh 
#!/bin/bash

date=$(date +%d)

echo $date

if [ ${date%2} -eq 0 ];

then

echo 'date is even'

else

echo 'date is odd'

fi

Code:
~ $ . test_even.sh 
08
date is odd

 $ date
Fri Nov  8 15:08:18 EET 2013

Please advise,thanks
Last edited by zarere; 11-08-2013 at 10:38 AM..
# 2  
Old 11-08-2013
You should use bash's integer arithmetics. And, btw, using a variable with the same name as a command works, but can become veeery misleading sometime! Try
Code:
echo $((10#${date}%2))

You can avoid the base 10 indicator if you use date +%e when assigning the variable.
This User Gave Thanks to RudiC For This Post:
zarere
# 3  
Old 11-08-2013
Quote:
Originally Posted by RudiC
You should use bash's integer arithmetics. And, btw, using a variable with the same name as a command works, but can become veeery misleading sometime! Try
Code:
echo $((10#${date}%2))

You can avoid the base 10 indicator if you use date +%e when assigning the variable.
Hi RudiC,

10x for the information but that still don't work even with:

Code:
echo $((10#${date}%2))

Code:
 cat test_even.sh 
#!/bin/bash

dates=$(date +%d)

echo $((10#${dates}%2))

if [ ${dates%2} -eq 0 ];

then

echo 'date is even'

else

echo 'date is odd'

fi

Code:
. test_even.sh 
0
date is odd

# 4  
Old 11-08-2013
OK. echo $((10#${dates}%2)) obviously yields 0, if [ ${dates%2} -eq 0 ]; doesn't. What conclusion would YOU draw?
This User Gave Thanks to RudiC For This Post:
zarere
# 5  
Old 11-08-2013
OK. echo $((10#${dates}%2)) obviously yields 0, if [ ${dates%2} -eq 0 ]; doesn't. What conclusion would YOU draw?

Obviously something in
Code:
[ ${dates%2} -eq 0 ];

is not correct or I'm missing something?

---------- Post updated at 04:56 PM ---------- Previous update was at 04:50 PM ----------

OK I got it now:

Code:
#!/bin/bash

dates=$(date +%d)

echo $((10#${dates}%2))

if [ $((10#${dates}%2)) -eq 0 ];

then

echo 'date is even'

else

echo 'date is odd'

fi

Now it's ok my bad and thanks again for the help:
Code:
~ $ . test_even.sh 
0
date is even

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