I've got a very ugly pipeline for analyzing web server logs (but nevermind the application; I've come across this in other scripts as well). I want to nicely comment the steps in the pipeline, but I can't seem to do it.
I know, for instance that in csh/sh/bash, a # begins a comment, and any subsequent \ or | will be ignored. I've tried playing with : but to little avail (I'm using bash v3.1).
Here's a sample of the pipeline:
Can you see why I might want to comment these steps?
I have a project where I have to use bzcat to uncompress a file and use that output as the data to run another program on.
I understand that you would do (bzcat filename.bz2 ! program name) but then how do you access that data in the c program??? Please help thanks (2 Replies)
Does anyone know how to answer this? I have tried many different commands, I just cant get it right.....
Search the file 'data' for all of the lines that contain the pattern 'unx122'
and put those lines in the file 'matches'. (2 Replies)
#! /bin/sed -nf
# Remove C and C++ comments, by Brian Hiles (brian_hiles@rocketmail.com)
# Sped up (and bugfixed to some extent) by Paolo Bonzini (bonzini@gnu.org)
# Works its way through the line, copying to hold space the text up to the
# first special character (/, ", '). The original... (1 Reply)
I must write a script to change all C++ like comments:
// this is a comment
to this one
/* this is a comment */
How to do it by sed? With file:
#include <cstdio>
using namespace std; //one
// two
int main() {
printf("Example"); // three
}//four
the result should be: (2 Replies)
Hi,
I am trying to calculate a few values using the below code but it dosent seem to be working.
for i in 1 2 3 4 5 6 7 8
do
j=`expr $i + 3`
x =`head -$j temp1|tail -1|cut -f24 -d","`
y =`head -$j temp1|tail -1|cut -f25 -d","`
c =`expr $x / $y`
echo "$c" >> cal_1
done
I am not... (4 Replies)
I need to read input from a file, and make sure nothing prints after column 72.
basically, ignore input after character 72 until the next newline character.
Any help is appreciated. I have been searching forever! (10 Replies)
Hello gurus - I must be missing something, or there is a better way - pls enlighten me
I'm on a Solaris 10 vm running the following pipeline to reduce some apache logs (actually lynx dumps of /server-status/ when threads are above a threshold) to a set of offending DDoS IP addresses.
awk... (10 Replies)
Hi
Can anybody please explain me the following script in detail
Value=`echo "if ( ${FACTOR} >= 1 ) {1}" | bc`
What does "{1}" mean to here ? (3 Replies)
Hello,
I am attempting to ssh to a server and run a set of commands on a remote set of servers. I am getting the following error below, I am thinking quotes may be the problem. This command works on the local machine in bash. Not when I ssh to a remote server. Basically the command should... (3 Replies)
Discussion started by: jaysunn
3 Replies
LEARN ABOUT LINUX
unbuffer
UNBUFFER(1) General Commands Manual UNBUFFER(1)NAME
unbuffer - unbuffer output
SYNOPSIS
unbuffer program [ args ]
INTRODUCTION
unbuffer disables the output buffering that occurs when program output is redirected from non-interactive programs. For example, suppose
you are watching the output from a fifo by running it through od and then more.
od -c /tmp/fifo | more
You will not see anything until a full page of output has been produced.
You can disable this automatic buffering as follows:
unbuffer od -c /tmp/fifo | more
Normally, unbuffer does not read from stdin. This simplifies use of unbuffer in some situations. To use unbuffer in a pipeline, use the
-p flag. Example:
process1 | unbuffer -p process2 | process3
CAVEATS
unbuffer -p may appear to work incorrectly if a process feeding input to unbuffer exits. Consider:
process1 | unbuffer -p process2 | process3
If process1 exits, process2 may not yet have finished. It is impossible for unbuffer to know long to wait for process2 and process2 may
not ever finish, for example, if it is a filter. For expediency, unbuffer simply exits when it encounters an EOF from either its input or
process2.
In order to have a version of unbuffer that worked in all situations, an oracle would be necessary. If you want an application-specific
solution, workarounds or hand-coded Expect may be more suitable. For example, the following example shows how to allow grep to finish pro-
cessing when the cat before it finishes first. Using cat to feed grep would never require unbuffer in real life. It is merely a place-
holder for some imaginary process that may or may not finish. Similarly, the final cat at the end of the pipeline is also a placeholder
for another process.
$ cat /tmp/abcdef.log | grep abc | cat
abcdef
xxxabc defxxx
$ cat /tmp/abcdef.log | unbuffer grep abc | cat
$ (cat /tmp/abcdef.log ; sleep 1) | unbuffer grep abc | cat
abcdef
xxxabc defxxx
$
BUGS
The man page is longer than the program.
SEE ALSO
"Exploring Expect: A Tcl-Based Toolkit for Automating Interactive Programs" by Don Libes, O'Reilly and Associates, January 1995.
AUTHOR
Don Libes, National Institute of Standards and Technology
1 June 1994 UNBUFFER(1)