tail

Using bash process substitution, I want to run two different commands on a file simultaneously. In this example it is not necessary but imagine that "cat /usr/share/dict/words" was a very expensive operation such as uncompressing a 50gb file. cat /usr/share/dict/words | tee >(head -1 > h.txt) >(tail -1 > t.txt) > /dev/null After this command I would expect h.txt to contain the first line of the words file "A", and t.txt to contain the last line of the file "Zyzzogeton". However what actually happens is that h.txt contains "A" but t.txt contains "argillaceo" which is about 5% into the file. Why

I need to wrap the Unix command "tail -f" in a BufferedInputStream. I don't want to simulate or mimic tail as stated by this question . Rather, I want to use tail, waiting for it to give me a new line. Your best bet is to use the Process class and read with a Scanner : Runtime r = Runtime.getRuntime() Process p = r.exec("tail -f") Scanner s = new Scanner(p.getInputStream()) while (s.hasNextLine()) { String line = s.nextLine() // Do whatever you want with the output. } hasNextLine() should block as it's waiting for more input from the input stream, so you will not be busy-waiting as data comes

What is the best way to read a 1 GB file that gets time series data logged in it and generate a real time graph with two of its columns (one time and other a number)? I see that you have different ways of tailign the file. Sounds like a good job for RRDTool . But if you want to stick with Python, I would use tail to stream the data into my program (this is assuming the file is continuously written to, otherwise a straight open() in Python will work). tail -F data.log | python myprogram.py myprogram.py could look something like: import sys p = ... # create a pylab plot instance for line in sys

Using heroku logs --tail which works great for a few minutes. Then it stops displaying the logs. It seems that the ssh connection is timing out and dying. There is no error or message. Working in Ubuntu 11.04 on wired conneciton. I added the following to ~/.ssh/config: ServerAliveInterval 5 But it didn't work. Do I need anything else in the config file? How do I know if it is doing anything? How can I monitor the traffic and see the keepalive request? I am looking at System Monitor but don't see anything every 5 seconds. Thanks. Have you done all of this: $ heroku config:add LOG_LEVEL=DEBUG $

I have a directory full of rolling log files that I would like to be able to use tail on. The files are named as such: name modified 00A.txt Dec 27 19:00 00B.txt Dec 27 19:01 00C.txt Dec 27 19:02 00D.txt Dec 27 19:03 On an older unix system, I'm trying to come up with a shell script that will tail the most recently modified file in a specific directory, and if that file gets administratively closed (rolls to the next file) I want the program to automatically begin tailing the new file without me having to break out of tail to rerun. tail -100f `ls -t | head -1` The desired behavior, given the

I would like to grep something like ==> *.sh <== . But it doesn't work, I can grep everything up to .sh <== but not get the wild card to work. What's the trick here? You need to grep for something like "==> .*\.sh <==" The .* part matches any character for any length, the \. part matches a dot. 来源： https://stackoverflow.com/questions/5906228/grep-for-text-with-wild-card-in-between