Bash scripting: detect first day of month

Question

I wrote three bash files:

1. incremental_backup
2. full_backup
3. execution

Now I want another bash script do the following :

if (date is the start of month 1/-/----)
then     
    invoke `full_back_up`
else
    invoke `incremental_backup`

How can I write this script?

Answer 1

Don't do this. Instead use two separate cron jobs to invoke your tasks.

15 5 1 * * scripts/full_back_up
15 5 2-31 * * scripts/incremental_backup

Answer 2

Try

if [ `date +%d` != "01" ] 
then
    incremental_backup
else
    full_backup
fi