Configure a Sendmail subject using crontab

Question

My cron job is running the following line:

*/40 * * * * cd /home/qa/prod/seo/casino &&  make testv   2> /dev/stdout | /usr/sbin/sendmail -t xxxx@gmail.com

As you can see I am using the sendmail package. The thing I don't manage to find out is how to add a subject to the currently-running cron schedule.

I've came across the following :

echo "Subject: Testing" | cat - /home/file1.out | /usr/sbin/sendmail -t xxxx@gmail.com

However, I have no idea whats the 'cat - /home/file1.out' pipeline does in this case, or how I can integrate it with my own.

Help would be appreciated!

Answer 1

cat - /home/file1.out is for the body of the message.

- means STDIN in this case, STDIN for cat.

[sgeorge@sgeorge-ld ~]$ echo "Subject: Testing" | cat - file 
Subject: Testing
TESTING TESTING
[sgeorge@sgeorge-ld ~]$ echo "Subject: Testing" | cat file 
TESTING TESTING

Actually you don't need it actually:

[sgeorge@sgeorge-ld ~]$ cat test 
Subject: Testing
TESTING TESTING
[sgeorge@sgeorge-ld ~]$ cat test | /usr/sbin/sendmail -t xxxxx@xxxxxx.com

The just above method will also work in the same way as below one works

echo "Subject: Testing" | cat file | /usr/sbin/sendmail -t xxxxx@xxxxxxxx.com 

For more understanding:

[sgeorge@sgeorge-ld ~]$ echo "Subject: Testing" | cat file -
TESTING TESTING
Subject: Testing
[sgeorge@sgeorge-ld ~]$ echo "Subject: Testing" | cat - file 
Subject: Testing
TESTING TESTING

So - is just an STDIN here.

Answer 2

The - in cat - tells cat to read the content from pipeline and print it to stdout, so that echo "Subject:Testing " | cat - /home/files1.out means combine "Subject: Testing" with content of files1.out.