Sending Email Alerts Through Cron

Cron is the Linux task scheduler that is responsible for making sure scripts run at their specified times. Cron is often used for backup scripts and running custom scripts. In the event a task runs into problems or errors Cron generally tries to email the local administrator of the machine. this means it tries to send an email to itself.
We can change this default behavior by changing the MAILTO variable (It won't work if you have not setup an email server or SMTP)
Setting MAILTO variable
Edit the crontab by entering crontab -e and add
MAILTO=your.email@your_provider.com
It should look something as below

Specify email for each script
If we don’t want all output to go to the same email address we can specify the output of a particular script to go to a different email address
0 8 * * * /mnt/dbbkup/Databkup/FULL_SCHEMA_BACKUPS/ETL/SQLs/load.sh | mail -s "QA Load 8AM" someaddress@email.com

If you don't want email alerts add ">/dev/null 2>&1" at the end of the command
0 8 * * * /mnt/dbbkup/Databkup/FULL_SCHEMA_BACKUPS/ETL/SQLs/load.sh >/dev/null 2>&1

How to find out Linux System is 32-bit or 64-bit

$ arch
x86_64

$ getconf LONG_BIT

64

$ file /sbin/init

/sbin/init: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, stripped

CRONTAB

# 1. Entry: Minute when the process will be started [0-60]
# 2. Entry: Hour when the process will be started [0-23]
# 3. Entry: Day of the month when the process will be started [1-28/29/30/31]
# 4. Entry: Month of the year when the process will be started [1-12]
# 5. Entry: Weekday when the process will be started [0-6] [0 is Sunday]

# Minute   Hour   Day of Month       Month          Day of Week        Command    
# (0-59)  (0-23)     (1-31)    (1-12 or Jan-Dec)  (0-6 or Sun-Sat)   
    0           2          12                   *                       *              /usr/bin/find


Use the command "crontab -e" to edit your crontab file.

Use the command "crontab -l" to list your crontab file.

SCP as a background process without using password

SCP as a background process without using password

To execute any linux command in background we use nohup as follows:

$ nohup SOME_COMMAND &
But the problem with scp command is that it prompts for the password (if password authentication is used). So to make scp execute as a background process do this:

$ nohup scp file_to_copy user@server:/path/to/copy/the/file > nohup.out 2>&1
Then press ctrl + z which will temporarily suspend the command, then enter the command:

$ bg
This will start executing the command in backgroud

Linux: Delete Files Older than x number of days

Delete files older than x number of days (in my case 5 days)

find /temp -type f -name '*.dmp' -mtime +5 -exec rm -rf {} \;