Command Linux not working "grep"

Question

I'm using the command grep in Linux to get a specific information from my output file, but I don't know why does not copy to the file.

When I use the command like that, it works

udevadm monitor --env | grep "ACTION"
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove
ACTION=remove

But, when I use the command like this, it does not copy to the "output.txt"

udevadm monitor --env | grep "ACTION" >> output.txt

This is because of buffering in the redirection, see [this question](http://stackoverflow.com/q/13858912/1331399) to see how to get around it. Short answer: add the `--line-buffered` option to the `grep` command. — Thor, Jun 11 '14 at 09:13
@ Thor thanks it's working now ...i just add the "--line-buffered" option like this , and it's working udevadm monitor --env | grep --line-buffered "ACTION" >> file.txt — Machete, Jun 11 '14 at 09:22

score 1 · Answer 1 · answered Jun 11 '14 at 09:07

1

Try :

udevadm monitor --env >> file ; cat file | grep "ACTION" >> result

tell me about file and result.

answered Jun 11 '14 at 09:07

Dinou

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1
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@ Dinou ..i used you're command, the two files are created ...in the first "file" i get all the information of the "udevadm monitor", but in the second file "result" nothing was copied to this file. – Machete Jun 11 '14 at 09:14
Can you type : `ll result` to know about the files rights... – Dinou Jun 11 '14 at 09:34

score 0 · Accepted Answer · answered Jun 11 '14 at 08:49

0

The command is correct. You must find the filtered lines in the end of output.txt. You can add tee between to see what is copied.

udevadm monitor --env | grep "ACTION" | tee >> output.txt

answered Jun 11 '14 at 08:49

Igor Chubin

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13
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thanks @Igor Chubin for you're quick reply....i used the command that you propose to me, but still not coping to the "output.txt"... the file is still empty :s – Machete Jun 11 '14 at 08:55
but the output was not empty? – Igor Chubin Jun 11 '14 at 09:05

Command Linux not working "grep"

2 Answers2