UnixSupport.com

Having to move large sums of data between boxes is part of an admins life… and sometimes those machines are across the country, and your moving a bunch of sensitive data, and the bosses want to make sure no one can sniff at it… ok, whatever boss

So here’s what I do, use friendly unix tar, and ssh pipe it to another machine.

Lemme show you some examples:
This shows you how to send files FROM the local machine TO a remote machine.

$ cd directory-with-files
$ tar cf - . | ssh username@remoteserver.com “cd /directory-to-put-files; tar xf -” [ENTER]

Ok, you may be asking me to explain this madness:
Change to a directory with files you want to transfer

tar cf - . - create a tar file, with the name “-”, which means output to screen, in the directory “.” (currently in, or right here)

| ssh username@remoteserver - setup an ssh connection to the remote server
“cd /directory-to-put-files; tar xf -” [ENTER] - once connected, change directorys on the local machine, and then EXTRACT that tar file named “-” or output to the screen.

In this case, the output to the screen will be piped thru ssh to the other computer and boom your set.

---

Now, in order to reverse the logic and transfer FROM a server TO the local machine:

$ cd directory-to-put-files
$ ssh username@remoteserver.com “cd /directory-to-get-files; tar cf - .” | tar xf - [ENTER]

Try it out

Ok, this might sound insane, but this is the type of question you get asked sometimes, or the situation where you need to know comes up.

I was once asked what the current working directory was of a process on the server… often times I don’t even think about it, however the script was writing files, and we had no idea where

I tracked it down to a pretty simple method

> ps -awux | grep [process]

root 90 0.0 0.0 1016 228 ?? Is 27Apr05 1:01.81 /usr/sbin/cron

> ls -l /proc/[pid from above, which is 90]/cwd

lrwxrwxrwx 1 root root 0 Nov 4 12:56 /proc/90/cwd -> /var/spool

And it’s current working directory is /var/spool

Neat

Ok, I feel stupid, however I never realized that I could search man pages!

For those that don’t know, unix offers a built in “manual” command called “man”… sometimes it’s helpful, sometimes it’s there just for reference. It’s easy

$ man command

in this case man ls

LS(1) FreeBSD General Commands Manual LS(1)

NAME
ls - list directory contents

SYNOPSIS
ls [-ABCFGHLPRTWabcdfghiklmnopqrstuwx1] [file …]

DESCRIPTION
For each operand that names a file of a type other than directory, ls
displays its name as well as any requested, associated information. For
each operand that names a file of type directory, ls displays the names
of files contained within that directory, as well as any requested, asso-
ciated information.[and on and on]

---

man is a great thing, however sometimes you end up forgetting the command your using, and thats when my new little friend helps out…

$ man -k search-scring[ENTER]

This is awsome, now I can find all the insane instances of locate man -k locate

cfree(3) - free up allocated memory
index(3) - locate character in string
locate(1) - find filenames quickly
locate.updatedb(8) - update locate database
memchr(3) - locate byte in byte string
mmap(2) - allocate memory, or map files or devices into memory
pthread_mutex_destroy(3) - free resources allocated for a mutex
rindex(3) - locate character in string
strchr(3) - locate character in string
strpbrk(3) - locate multiple characters in string
strrchr(3) - locate character in string
strstr(3), strcasestr(3), strnstr(3) - locate a substring in a string
usbhid(3), hid_get_report_desc(3), hid_use_report_desc(3), hid_dispose_report_desc(3), hid_start_par
se(3), hid_end_parse(3), hid_get_item(3), hid_report_size(3), hid_locate(3), hid_usage_page(3), hid_
usage_in_page(3), hid_init(3), hid_get_data(3), hid_set_data(3) - USB HID access routines
whereis(1) - locate programs
which(1) - locate a program file in the user’s path

Give it a whirl!

Sometimes you gotta grant Mysql permissions for usernames… so here’s how I do it.

$ mysql -u root -p

Enter password: [password] [ENTER]
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 14806 to server version: 4.1.11

Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the buffer.

mysql> use mysql;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> insert into db values (’IP or Hostname‘, ‘DB Name‘, ‘Username‘, ‘Y’, ‘Y’, ‘Y’, ‘Y’, ‘Y’, ‘Y’, ‘N’, ‘Y’, ‘Y’, ‘Y’);

mysql> insert into user values (’IP or hostname‘, ‘Username‘, ‘xxx’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’, ‘N’);

the XXX is where the password will exist.

mysql> update user set Password=password(’Password‘) where user=’Username‘;

SSH Keys are an awsome tool.. and they’ll save your fingers from typing your password 10,000 times a day. They’re also really easy to setup:

login to your main server, or home machine as the user you normally are logged in as.

username@yourserver.com [16:00:51]
[~/.ssh]: /usr/bin/ssh-keygen -t dsa
Generating public/private dsa key pair.
Enter file in which to save the key (/home/username/.ssh/id_dsa): [ENTER]
Enter passphrase (empty for no passphrase): [ENTER]
Enter same passphrase again: [ENTER]
Your identification has been saved in /root/.ssh/id_dsa.
Your public key has been saved in /root/.ssh/id_dsa.pub.
The key fingerprint is:
ff:ff:ff:ff:ff:ff:ff:ff:ff:ff:1e:00:fb:d5:57:45:20:c3 username@yourserver.com

username@yourserver.com [16:00:59]
[~/.ssh]: cat id_dsa.pub

ssh-dss [EDITED OUT HUGE TEXT HASH ] username@yourserver.com

Copy the entire output from your server to your clipboard.

Now login to the remote server you want to be able to access without a password and:

$ vi ~/.ssh/authorized_hosts

go to the bottom of the file and insert and paste the line, then [ESC] [ESC] :wq!

and give it a test

$ ssh username@remoteserver.com

when dealing with logs, getting to the end of a huge file is a huge pain. Thats why tail was created.

tail is on most machines and can be used as such

---

tail filename[ENTER]

by default that shows the last 5 lines of the file.

---

tail -n 1000 filename

will show the last -n # of lines.

---

tail also has another useful feature, which is show the log file as it’s written to:

so

tail -f filename

will stay active showing you the log file as it’s written to on the screen. You can press Control and C at the same time to break out.

Give it a try on a web log file and hit a site, you’ll see your visit!