I have a file that is constantly being written to/updated. I want to find the last line containing a particular word, then print the last column of that line.
The fi
Execute this on the file:
awk 'ORS=NR%3?" ":"\n"' filename
and you'll get what you're looking for.
You don't see anything, because of buffering. The output is shown, when there are enough lines or end of file is reached. tail -f
means wait for more input, but there are no more lines in file
and so the pipe to grep
is never closed.
If you omit -f
from tail
the output is shown immediately:
tail file | grep A1 | awk '{print $NF}'
@EdMorton is right of course. Awk can search for A1
as well, which shortens the command line to
tail file | awk '/A1/ {print $NF}'
or without tail, showing the last column of all lines containing A1
awk '/A1/ {print $NF}' file
Thanks to @MitchellTracy's comment, tail might miss the record containing A1
and thus you get no output at all. This may be solved by switching tail
and awk
, searching first through the file and only then show the last line:
awk '/A1/ {print $NF}' file | tail -n1
ls -l | awk '{print $9}' | tail -n1
To print the last column of a line just use $(NF):
awk '{print $(NF)}'
Not the actual issue here, but might help some one: I was doing awk "{print $NF}"
, note the wrong quotes. Should be awk '{print $NF}'
, so that the shell doesn't expand $NF
.