Bash: Use command output as argument for next command in pipe

_Mike_ · 2011-05-20 15:02:43

I'm trying to do this:

tail -f /var/logfile | grep -C 0 text | mail -s "OUTPUT OF GREP" mail@mail.com

How can I do this?

demian · 2011-05-20 15:14:01

maybe with a variable

tail -f /var/logfile | grepout=$(grep -C 0 test) | mail -s "$grepout" mail@mail.com

// nope, doesn't work

Last edited by demian (2011-05-20 15:17:19)

karol · 2011-05-20 15:14:21

Haven't tested it but try

mail -s $(tail -f /var/logfile | grep -C 0 text) mail@mail.com

Edit: Are you sure it will work with 'tail -f'?
Seems that the subject can't contain certain characters:

[karol@black ~]$ mail -s $(tail /var/log/kernel.log | grep -C 0 detected) foo@bar.com
18:05:11 contains invalid character ':'
kernel: contains invalid character ':'
[ contains invalid character '['
8.433910] contains invalid character ']'
4-0:1.0: contains invalid character ':'
^C

How will you escape multiple newlines?

Last edited by karol (2011-05-20 15:20:07)

demian · 2011-05-20 15:19:18

I think tail -f will always intefere. You'd have to use normal tail and instead create a loop to check it every ~ secs or so.

karol · 2011-05-20 15:23:23

How about putting the output inside the e-mail?

echo "$(tail /var/log/kernel.log | grep -C 0 swap)" | mail -s somesubject foo@bar.com

This works nicely.

falconindy · 2011-05-20 15:29:17

tail -f /var/logfile | stdbuf -oL grep  text | while read text; do mail -s "$text" mail@mail.com; done

_Mike_ · 2011-05-20 15:33:15

It's important that the output goes to the subject.

To simplify , How would you do this?
cat file | grep word | command -x grepoutput

falconindy · 2011-05-20 15:35:11

Did you try what I posted? It does exactly that.

http://partmaps.org/era/unix/award.html

_Mike_ · 2011-05-20 15:58:50

falconindy: you replied fast I had to reload the page to see your comment

I'm testing your commnad, I still dont fully understand it. But for the little I tested it's not working.
I executed it, waited a bit for many new lines to be added to the log file. Only after I finish the command with CONTROL+C, one mail is send with only 1 of the log lines added to the subject.

falconindy · 2011-05-20 16:03:39

Right... because there's no body to the message.... i suppose you could fix that, hackishly...

tail -f /var/logfile | stdbuf -oL grep  text | while read text; do mail -s "$text" mail@mail.com </dev/null; done

_Mike_ · 2011-05-20 16:25:51

Thanks falconindy. It works now, you really are a Bash Ninja.

stqn · 2011-05-22 13:24:50

Please mark as solved...

Arch Linux

#1 2011-05-20 15:02:43

Bash: Use command output as argument for next command in pipe

#2 2011-05-20 15:14:01

Re: Bash: Use command output as argument for next command in pipe

#3 2011-05-20 15:14:21

Re: Bash: Use command output as argument for next command in pipe

#4 2011-05-20 15:19:18

Re: Bash: Use command output as argument for next command in pipe

#5 2011-05-20 15:23:23

Re: Bash: Use command output as argument for next command in pipe

#6 2011-05-20 15:29:17

Re: Bash: Use command output as argument for next command in pipe

#7 2011-05-20 15:33:15

Re: Bash: Use command output as argument for next command in pipe

#8 2011-05-20 15:35:11

Re: Bash: Use command output as argument for next command in pipe

#9 2011-05-20 15:58:50

Re: Bash: Use command output as argument for next command in pipe

#10 2011-05-20 16:03:39

Re: Bash: Use command output as argument for next command in pipe

#11 2011-05-20 16:25:51

Re: Bash: Use command output as argument for next command in pipe

#12 2011-05-22 13:24:50

Re: Bash: Use command output as argument for next command in pipe

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