 Register |
| Unregistered users click here to register registered users can post their website here |
 Science Humor: |
Understanding is always the understanding of a smaller problem
in relation to a bigger problem.
-- P.D. Ouspensky
|
| Chuck Norris Humor: |
Before science was invented it was once believed that autumn occurred when Chuck Norris roundhouse kicked every tree in existence.
|
|
 |
| Regenerate a id_rsa.pub key from a private id_rsa key - |
|---|
ssh-keygen -y -f id_rsa >id_rsa.pub
|
| Password-less ssh login - |
|---|
// description of your code here
http://rcsg-gsir.imsb-dsgi.nrc-cnrc.gc.ca/documents/internet/node31.html
|
| How to create an alias in Unix systems - |
|---|
// go to our home path, edit the '.profile' file and append the next line
alias ll='ls -ltr'
|
| Execute a Unix Command with Node.js - |
|---|
// http://nodejs.org/api.html#_child_processes
var sys = require('sys')
var exec = require('child_process').exec;
var child;
// executes `pwd`
child = exec("pwd", function (error, stdout, stderr) {
sys.print('stdout: ' + stdout);
sys.print('stderr: ' + stderr);
if (error !== null) {
console.log('exec error: ' + error);
}
});
// or more concisely
var sys = require('sys')
var exec = require('child_process').exec;
function puts(error, stdout, stderr) { sys.puts(stdout) }
exec("ls -la", puts);
|
| Tail Log Output with Node.js - |
|---|
// http://nodejs.org/api.html#_child_processes
var sys = require('sys')
var spawn = require('child_process').spawn;
var filename = process.ARGV[2];
if (!filename)
return sys.puts("Usage: node ");
var tail = spawn("tail", ["-f", filename]);
sys.puts("start tailing");
tail.stdout.on("data", function (data) {
sys.puts(data);
});
// node tail.js development.log |
| faster line count with grep rather than wc - |
|---|
wc can be dramatically slower than desirable if all you want is a count of lines in a file (e.g., ~6 minutes vs. the grep technique shown below, which took 10 seconds).
grep -c '\n' filename
|
| epoch2gmt - |
|---|
Convert Unix time string to a date/time group
#!/usr/bin/perl
use warnings;
use strict;
my $time = shift;
die "Usage: $0 [TIME_IN_SECS_SINCE_EPOCH]\n" unless $time;
if ( length($time) >10 ) {
$time = substr($time, 0, 10);
}
my @mon = qw( Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec );
my @day = qw( Sun Mon Tue Wed Thu Fri Sat );
my ($sec,$min,$hour,$mday,$mon,$year,$wday,$yday,$isdst)
= gmtime($time);
printf "%4d-%02d-%02d %02d:%02d:%02d (%s %02d %s %04d)\n",
$year + 1900, $mon + 1, $mday, $hour, $min, $sec,
$day[$wday], $mday, $mon[$mon], $year + 1900;
|
| unix domain socket client - |
|---|
// description of your code here
#include
#include
#include
#include
#include
#define UNIX_DOMAIN "/tmp/UNIX.domain"
int main(void)
{
int connect_fd;
int ret;
char snd_buf[1024];
int i;
static struct sockaddr_un srv_addr;
//creat unix socket
connect_fd=socket(PF_UNIX,SOCK_STREAM,0);
if(connect_fd<0)
{
perror("cannot create communication socket");
return 1;
}
srv_addr.sun_family=AF_UNIX;
strcpy(srv_addr.sun_path,UNIX_DOMAIN);
//connect server
ret=connect(connect_fd,(struct sockaddr*)&srv_addr,sizeof(srv_addr));
if(ret==-1)
{
perror("cannot connect to the server");
close(connect_fd);
return 1;
}
memset(snd_buf,0,1024);
strcpy(snd_buf,"message from client");
//send info server
for(i=0;i<4;i++)
write(connect_fd,snd_buf,sizeof(snd_buf));
close(connect_fd);
return 0;
}
|
| unix domain socket server - |
|---|
// description of your code here
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define UNIX_DOMAIN "/tmp/UNIX.domain"
int main(void)
{
socklen_t clt_addr_len;
int listen_fd;
int com_fd;
int ret;
int i;
static char recv_buf[1024];
socklen_t len;
struct sockaddr_un clt_addr;
struct sockaddr_un srv_addr;
listen_fd=socket(PF_UNIX,SOCK_STREAM,0);
if(listen_fd<0)
{
perror("cannot create communication socket");
return 1;
}
//set server addr_param
srv_addr.sun_family=AF_UNIX;
strncpy(srv_addr.sun_path,UNIX_DOMAIN,sizeof(srv_addr.sun_path)-1);
//unlink(UNIX_DOMAIN);
//bind sockfd &addr
ret=bind(listen_fd,(struct sockaddr*)&srv_addr,sizeof(srv_addr));
if(ret==-1)
{
perror("cannot bind server socket");
close(listen_fd);
unlink(UNIX_DOMAIN);
return 1;
}
//listen sockfd
ret=listen(listen_fd,1);
if(ret==-1)
{
perror("cannot listen the client connect request");
close(listen_fd);
unlink(UNIX_DOMAIN);
return 1;
}
printf("server started...\n");
//have connect request use accept
len=sizeof(clt_addr);
com_fd=accept(listen_fd,(struct sockaddr*)&clt_addr,&len);
if(com_fd<0)
{
perror("cannot accept client connect request");
close(listen_fd);
unlink(UNIX_DOMAIN);
return 1;
}
//read and printf sent client info
printf("\n=====info=====\n");
for(i=0;i<4;i++)
{
memset(recv_buf,0,1024);
int num=read(com_fd,recv_buf,sizeof(recv_buf));
printf("Message from client (%d)) :%s\n",num,recv_buf);
}
close(com_fd);
close(listen_fd);
unlink(UNIX_DOMAIN);
return 0;
}
|
| Low disk alert - |
|---|
#!/bin/bash
# Tested Under FreeBSD and OS X
FS="/usr"
THRESHOLD=90
OUTPUT=($(LC_ALL=C df -P ${FS}))
CURRENT=$(echo ${OUTPUT[11]} | sed 's/%//')
[ $CURRENT -gt $THRESHOLD ] &&echo "$FS file system usage $CURRENT" | mail -s "$FS file system" you@example.com
|
|
|
Jobs:
