Way to redirect output to a file without buffering on unix/linux

stdoutunix

I have a long running batch process that outputs some debug and process information to stdout.
If I just run from a terminal I can keep track of 'where it is' but then the data gets too much and scrolls off the screen.

If I redirect to output to a file '> out.txt' I get the whole output eventually but it is buffered so I can no longer see what it is doing right now.

Is there a way to redirect the output but make it not buffer its writes?

Best Answer

You can explicitly set the buffering options of the standard streams using a setvbuf call in C (see this link), but if you're trying to modify the behaviour of an existing program try stdbuf (part of coreutils starting with version 7.5 apparently).

This buffers stdout up to a line:

stdbuf -oL command > output

This disables stdout buffering altogether:

stdbuf -o0 command > output

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Linux/Unix – SSL Certificate Location Guide

For system-wide use, OpenSSL should provide you /etc/ssl/certs and /etc/ssl/private. The latter of which will be restricted 700 to root:root.

If you have an application that doesn’t perform initial privilege separation from root, then it might suit you to locate them somewhere local to the application with the relevantly restricted ownership and permissions.

How to make (non-gnu-)grep ignore binary files

Building on the previous answer, you can use the "file" command to identify text files, and then limit your grep to only those files. For example:

  find dir -type f -print |
    xargs file |
    grep text |
    cut -f1 -d: |
    xargs grep "expression"

That's:

Find all files in directory "dir"
Pass these as arguments to "file"
Look for output from "file" containing the word "text"
Chop out the first colon-delimited field and use it as a filename
Search these files using grep.

This will fail in the case of filenames containing whitespace or colons, but will otherwise do what you want.

Best Answer

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