grep the adb logcat & write the output to a text file

Edit: This seems to work

 ./adb logcat |grep --line-buffered  ABC >a.txt

I can explain you what is happening heres. Hope someone can derive a solution from that.If you run the following command in terminal

cat |grep "ABC"

and start entering lines of text, you can see that grep immediately outputs any lines that contains.

 cat somefile.txt | grep "ABC" 

will print all lines that contains 'ABC' to the terminal, as expected.

But if you run

cat |grep ABC >a.txt

and start entering text on the terminal, you can see that the file is not written until you enter an EOF character (Ctrl+ D) and make cat terminate.

But using --line-buffered gives output in the expected way

cat |grep --line-buffered  ABC >a.txt

Try adb logcat | grep ABC | tee out

This is working for me:

./adb logcat | grep ABC | dd of=/home/levex/dump.txt

Explanation: ./adb logcat opens the logcat, and then it goes through a pipe to grep ABC which filters the lines to those containing ABC, and then again through a pipe to dd of=/home/levex/dump.txt to finally print it to a file. of=xxx parameter sets the output file.

I think there is a problem with grep buffering. You can try something like this:

./adb logcat | grep --line-buffered ABC > std.txt

It should be the same problem for chained grep.

EDIT: A similar question can be found here: Why no output is shown when using grep twice?.