[SOLVED] [sSMTP] Right way for newline in body?

littlebigman · 10-03-2021, 06:22 AM

Hello,

I'm using the following code to send an email once a week through CRON to check free disk space on a host.

For some reason, the body is either a bit messy, or empty altogether:

Code:

~# cat show.free.disk.space.bash
#!/bin/bash

#This works fine when run manually at the command line
CURRENT=$(df / | grep / | awk '{ print $5}' | sed 's/%//g')

# Body: \Root partition 47 0.000000ull.
printf "To: me@isp.com\nSubject: Free Disk Space\n\n\Root partition $CURRENT% full." | ssmtp me@isp.com

# Empty body :-/
printf "To: me@isp.com\nSubject: Disk Space Alert\nRoot partition $CURRENT% full." | ssmtp me@isp.com

Any idea why?

Thank you.

boughtonp · 10-03-2021, 06:35 AM

See "man printf" - you need "%%" for a literal percent character.

But removing a percent sign just to re-add it again makes no sense, nor mixing grep/awk/sed like that (any one of them can do it with a single command) - and if you check "man df" you'll see you can simply specify the column you want, then use just sed to delete the headers (no idea why there isn't a df parameter to suppress that.)

Also, instead of embedding a variable you should use printf how it is intended to be used:

Code:

printf 'Root partition %s full.' $(df --output=pcent / | sed 1d)

or

Code:

CURRENT=$(df --output=pcent / | sed 1d)
printf 'Root partition %s full.' "$CURRENT"

In your second example, the body is empty because there is no body - you must separate it from the headers with two lines, as in your first example.

shruggy · 10-03-2021, 07:31 AM

Quote:

Originally Posted by boughtonp

then use just sed to delete the headers (no idea why there isn't a df parameter to suppress that.)

But findmnt has it:

Code:

findmnt -nouse% /

Interestingly enough, findmnt and di (both SysV and BSD-style percentage) give me a slightly different result than df:

Code:

$ df --o=pcent /
Use%
 75%
$ findmnt -nouse% /
 74%
$ di -n -f1 /
  74%
$ di -n -f2 /
  74%

Code:

$ df -h --o=size,used /
 Size  Used
  50G   38G
$ expr 38 \* 2
76
$ df --o=size,used /
1K-blocks     Used
 52399108 38987876
$ bc<<<'scale=1;38987876*100/52399108'
74.4
$ findmnt -osize,used /
SIZE  USED
 50G 37.2G
$ di  -fbBu /
    Size     Size     Used
   50.0G    50.0G    37.2G
$ bc<<<'37.2*2'
74.4

littlebigman · 10-03-2021, 09:53 AM

Thank you.

Code:

#!/bin/bash

CURRENT=$(df --output=pcent / | sed 1d)

printf 'To: me@isp.com\nSubject: Disk space\n\nRoot partition %s full.'  "$CURRENT" | ssmtp me@isp.com