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My SysAd Blog

My SysAd Blog
My UNIX-based blog covers a collection of tips for installations, programming, scripting, configuration, SQL, maintenance, troubleshooting, and command line syntax. What exactly is UNIX? Unix stands for UNiplexed Information and Computing System--ori

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Display the Structure of a Nisplus Table
2008-03-09 10:45:00
Building on the last post, I am using the niscat -o flag to display the structure of a common nisplus table. In the example below, the run shows the passwd table and its specific metadata/attribute information. Here is the syntax.# niscat -o passwd.org_dirObject Name : "passwd"Directory : "org_dir.esofthub.com."Owner : "esoft.esofthub.com."Group : "admin.esofthub.com."Access Rights : ----rmcdrmcdr---Time to Live : 12:0:0Creation Time : Sun Feb 24 18:22:47 2008Mod. Time : Sun Feb 24 18:22:47 2008Object Type : TABLETable Type : passwd_tblNumber of Columns : 8Character Separator : :Search Path :Columns : [0] Name : name Attributes : (SEARCHABLE, TEXTUAL DATA, CASE SENSITIVE) Access Rights : r---r---r---r--- [1] Name : passwd Attributes : (TEXTUAL DATA) Access Rights : ----rm--r---r--- [2] Name : uid ...
More About: Display , Structure

List Objects and Tables in Nisplus
2008-03-09 09:50:00
I have had a few search queries (metadata) via MyBlogLog analytics from readers who were searching for commands to show Nisplus objects and tables. Frankly speaking, I neglected posting much about this legacy name service (earlier on) because I did not really think it was worthwhile. But apparently, there seems to be a decent number of organizations still using it. At any rate, here is an example run.Show the objects# nislsesofthub.com.:org_dirgroups_dirShow the tables# nisls org_dirorg_dir.esofthub.com.:passwdgroupa uto_masterauto_homebootparamscredethersho stsipnodesmail_aliasessendmailvarsnetmask snetgroupnetworksprotocolsrpcservicestime zoneclient_infoauth_attrexec_attrprof_att ruser_attraudit_userOther posts on nisplus
More About: Tables , List , Objects

Add DES Credential For a Client Workstation
2008-03-02 12:37:00
If you want to add a credential for a workstation, you will need to make an entry into the niscred.org_dir table on the server. This example demonstrates what is done on the server side and workstation side. There are third party tools out there to manage credentials, but personally I like using the command line. Here is what a colleague and I did to support a NIS+ server change.On ServerC shell# setenv PATH $PATH:/usr/lib/nisBourne or Korn Shell# PATH=$PATH:/usr/lib/nis; export PATH# nisclient -c -o -d esofthub.com esoft# nisaddcred -p unix.esoft@esofthub.com -P esoft.esofthub.com. des# nisgrpadm -a admin.esofthub.com esoft.esofthub.com.On Workstation C shell# setenv PATH $PATH:/usr/lib/nisBourne or Korn Shell# PATH=$PATH:/usr/lib/nis; export PATH# nisclient -i -d esofthub.com -h esoftsvr -a IPADDRESS
More About: Credential , Client

Dump Sybase Database to File
2008-02-27 12:11:00
I had a reader ask me offline how to transfer a legacy database to another instance of a database management system (DBMS) on a separate server/workstation. The reader was trying to extract historical statistics via a test database (on a test server) without affecting the production database. I recommended dumping the entire database to a flat file and then writing (tar) the file to tape. I was uncertain if my response answered the reader's initial question but this is one way I dealt with a relatively small database (less than 50 megabytes) a few years ago. By the way, the sequence below assumes the receiving Sybase database was appropriately named and sized when it was created.Login into production DBMS1> use master2> go1> dump database yourdb to "/tmp/mydatabase.dat"2> go1> quit2> goArchive flat file to tape (assumes a tape drive is attached)# cd /tmp# tar cvfp /dev/rmt/0 mydatabase.datMove tape media to receiving server/workstation (assumes a tape drive is attached)# cd /tmp-...
More About: File , Database

Troubleshooting the "su: No shell" error
2008-02-24 10:54:00
The other day we had a problem with a system account. At first we did not notice the ?su: No shell? error on the console (headless server) but after a few reboots it was fairly evident. The message gave us enough feedback to determine the substitute user or su command was having a problem with a particular account. To ascertain which system account, we invoked a sequential step-through of the startup scripts.In the end, it appears that a third party application used to manage NIS+ had locked and changed the account?s shell to something unknown (by design) due to multiple login failures. The account was restored to its original shell.# su - esofthub -c "myscript"su: No shellView locked account# niscat passwd.org_dir | grep esofthubesofthub:*LK*:1005:10:esofthub test:/home/esofthub:/bin/sh.locked:13933: :::::Modify with third party applicationAfter the modification# su - esofthub -c "myscript"Visit Ucertify's challenge winners' blogs: Ax0N and armando For Files OnlyIf you are using t...
More About: Shell , Error , Troubleshooting

Using Z Shell Brace Expansion to Create Test Files
2008-02-18 13:20:00
Here is a convenient way of creating test files using the powerful Z Shell . I have been using this shell for a short while, and I am quickly becoming a fan of it. I used it to support transfer speed tests. To support these tests, I created a specified number of files that varied in size (1MB, 5MB, 10MB, 50MB, 100MB, 500MB, etc). Here is a straightforward one-liner mkfile example of creating 50 x 12MB files and a few others using zsh?s brace expansion.# zsh# mkfile 12m {1..50}.tst# ls -ltotal 122960-rw------T 1 root other 12582912 Feb 18 20:04 1.tst-rw------T 1 root other 12582912 Feb 18 20:04 2.tst-rw------T 1 root other 12582912 Feb 18 20:04 3.tst-rw------T 1 root other 12582912 Feb 18 20:04 4.tst-rw------T 1 root other 12582912 Feb 18 20:04 5.tst...Other examples...# touch {1..5}.testfile# ls -ltotal 0-rw-r--r-- 1 root other 0 Feb 18 20:07 1.testfile-rw-r--r-- 1 root other 0 Feb 18 20:07 2.testfile-rw-r--...
More About: Test , Files , Create , Expansion

Permanently Remove Data on UNIX Hard Drives
2008-02-13 16:37:00
It is fairly common for companies to dispose of their obsolete hard drives. However, most of them want to ensure all data is shredded from the hard drives. Finding a Windows-based wipe program was fairly easy, but finding a UNIX-based program took a little more searching. BCWipe is a program that will wipe a UNIX-based hard drive clean. The BCWipe website claims their multi-platform UNIX version is intended to give you a confidence that your deleted files cannot be recovered by an intruder. BCWipe repeatedly overwrites special patterns to the files to be destroyed.Note: Most likely you will have to compile the source code for your particular platform architecture.BCWipe for UNIX offers the following wiping schemes per their site.1. US DoD 5220.22-M standard (7 passes with verification)2. User-defined number of passes3. Peter Gutmann's 35 pass schemeBCWipe for UNIX is designed as a multi-platform solution. Here is their supported list of various UNIX flavors.Linux 2.0-2.6FreeBSD 3...
More About: Unix , Data , Hard , Hard drives

Automounting a User?s Home Directory
2008-02-09 17:26:00
A couple colleagues of mine were trying to execute a program on the server that required a special initialization environment, which was called from the /home/loginuser path. The login, loginuser, was not part of the server?s name service domain. It was a local account on a remote workstation. After a little discussion, they added this syntax to the /etc/auto_home file. Here is a run to illustrate the aforementioned.# vi /etc/auto_home# Home directory map for automounter#loginuser esoft:/export/home/USERS/&#* server:/export/home/USERS/&#+auto_hom e:wq!# automount -vautomount: /net mountedautomount: /home mountedautomount: /xfn mountedautomount: /export/opt mountedautomount: no unmounts# cd /home/loginuser# ls -a. .. .cshrc myblog esoftfile topblog
More About: Directory , User , Tomo

Troubleshoot POP3 Mail Server with Telnet
2008-02-05 14:46:00
I am finally getting an opportunity to write a post. I have been so busy with upgrades lately and had to put off writing for awhile.The other day I had a number of users complaining about not being able to fetch mail to their mail client, MS Outlook. As usual, I attempted to duplicate the error. The error message was reporting unable to connect to the mail server. At that point, I decided to telnet the Post Office Protocol or POP3 port, 110, via the command line interface. Sure enough, I had a problem.Note: The ?before and after? command line examples are only for illustration purposes.# telnet server 110Trying 192.1xx.xx.xxx...telnet: Unable to connect to remote host: Connection refusedI started thinking there was a problem with the inetd.conf file. After reviewing the file, I noticed the pop3 service was commented out. The appropriate change was made and inetd was restarted. Problem resolved.# telnet server 110Trying 192.1xx.xx.xxx...Connected to server.Escape character is '^]'...
More About: Mail , Server , Troubleshoot , Telnet

IT Certification Self-Help Portal
2008-01-22 18:20:00
I found this technical self-help website, uCert ify.com, very interesting and wanted to share it with some of the readers. The company has been online since 1999. They are offering PrepKits which are interactive software programs that help you learn, track your progress, identify areas for improvement and simulate the actual exam. I sampled a few of their demo quizzes, but I mainly focused on their database kits because I am thinking about an Oracle certification in the near-term. On my initial run through, I found the practice test questions to be relevant and comprehensive, not just some cheesy Q&A effort.I downloaded their Oracle 10G kit and obtained a key for it. It was a quick download via VDSL and was extremely easy to setup. I did not have any problems obtaining a key from uCertify. For the premium version, I took a couple of its timed practice tests along with its timed final. I thought the final test was a bit more difficult than the practice tests which was probably by ...
More About: Portal , Certification

IT Certification Self-Help Portal
2008-01-22 18:20:00
I found this technical self-help website, uCertify.com, very interesting and wanted to share it with some of the readers. The company has been online since 1999. They are offering PrepKits which are interactive software programs that help you learn, track your progress, identify areas for improvement and simulate the actual exam. I sampled a few of their demo quizzes, but I mainly focused on their database kits because I am thinking about an Oracle certification in the near-term. On my initial run through, I found the practice test questions to be relevant and comprehensive, not just some cheesy Q&A effort.I downloaded their Oracle 10G kit and obtained a key for it. It was a quick download via VDSL and was extremely easy to setup. I did not have any problems obtaining a key from uCertify. For the premium version, I took a couple of its timed practice tests along with its timed final. I thought the final test was a bit more difficult than the practice tests which was probably by ...
More About: Portal , Certification

Parse XML Records with Perl Script
2008-01-12 11:42:00
A colleague, Mahlon Anderson, and I were thinking of ways of splitting up a fairly large XML file, which had approximately 27K records in it. I wanted to split this file into smaller ones, each having about 250-300 records, because my former web host service kept complaining about constant CPU quota overloads during uploads.With the service, I had plenty disk space and plenty bandwidth but limited CPU usage. Apparently, I didn?t notice that sticky point in the fine print while signing up for the service. At any rate, here is Mahlon's "quick and dirty" XML Perl parser. By the way, a different and more extensive parsing implementation was later used as the permanent solution.# vi parser.pl#!/usr/bin/perl$file = @ARGV[0];open(_FH, "$count = 0; $files_counter=1;$max_records = 300; while (_FH){ if($count == 0) { $filename = $file . "_part_" . $files_counter; open(FH2, "> $filename") or die "Unable to open file: $filename "; $count++; } ...
More About: Script , Records , Cord

Split XML Records with Perl Script
2008-01-12 11:42:00
A colleague, Mahlon Anderson, and I were thinking of ways of splitting up a fairly large XML file, which had approximately 27K records in it. I wanted to split this file into smaller ones, each having about 250-300 records, because my former web host service kept complaining about constant CPU quota overloads during uploads. A Perl splitter quickly came to mind.With the web host service, I had plenty disk space and plenty bandwidth but limited CPU usage. Apparently, I didn?t notice that sticky point in the fine print while signing up for the service.A different splitting implementation was later used as the permanent solution, but here is Mahlon's "quick and dirty" XML Perl splitter-- printed with his permission of course.# vi split.pl#!/usr/bin/perl$file = @ARGV[0];open(_FH, "$count = 0;$files_counter=1;$max_records = 300; while (_FH){if($count == 0){$filename = $file . "_part_" . $files_counter;open(FH2, "> $filename") or die "Unable to open file: $filename ";$count++;}if (grep ...
More About: Script , Records , Split

FEATURE_ERROR_USER_OPEN_NO_ACCESS
2008-01-11 03:45:00
As I do practically every morning along with millions of others around the world, I logged into my Yahoo.com email account to check mail. To my chagrin, I was unable to login, and to make matters worse, my user ID/password combination wasn't recognized by the system. My first thoughts were "CAPS LOCK," or forgotten (which I rarely do) password , or hacked, or TOS violations (on what basis??) or corrupted cookies ? who the heck knows. Then I decided to have my password recovered to an alternate email address (gmail), but I was still darn sure I knew my password. For ?you know what and grins,? I made an attempt to recover it. But my user ID wasn't even recognized by the system. Here is the message I received after entering my user ID and answering a question about ever using a credit card or not.----Sorry That You're Having Trouble Signing InWe know that not being able to sign in can be frustrating, so we'll try to make this as quick and easy as possible. To get started, enter yo...

Finding Open Files with lsof Command
2008-01-09 12:30:00
When a file is in use by a process, it is possible to delete the file - OR at least it may appear that is the case. The filename is no longer visible via the ls command, but it is there until the process using it exits.For example, let's say Sysadmin1 runs a sniffer process in the background to capture and save packets to a file. The capture file starts growing bigger over time. Instead of killing the process, he/she simply deletes the capture file, thinking this will recover the disk space. It doesn't. Believing everything is well, Sysadmin1 goes home.Now Sysadmin2 shows up and notices the box is running out of disk space. Naturally, the admin wants to figure out what?s rapidly consuming disk space. The easiest way for the SysAd to locate the growing file is to use the lsof command.Another instance the lsof would be helpful is when a filesystem refuses to unmount due to open files.Here are a few practical examples of using the lsof command.To list all the open files on the var ...
More About: Open , Files , Command

Setup Mail Client on UNIX-based System
2008-01-07 14:24:00
In the last post, a mail server setup was demonstrated. This post will demonstrate the setup of a mail client. Again, the setup of mail client is fairly straightforward. Here is the run.On the client side, ensure the /var/mail directory is present.# ls -l /var/mailIf not, create it.# cd /var# mkdir mailNow modify the client's /etc/vfstab file# vi /etc/vfstabesoft:/var/mail - /var/mail nfs - yes -:wq!Now mount /var/mail# mount /var/mailVerify the /var/mail is actually being shared from the mail server# cd /var/mail# df -k .
More About: Mail , System , Unix , Setup , Client

Setup Mail Server on UNIX-based System
2008-01-07 14:04:00
The last post made me think about setting up a mail server on my eBay purchased UNIX-based box at home. As I recalled from a few years ago, this was a fairly straightforward task to accomplish. The task primarily dealt with ensuring the server?s /var partition was amply sized and its /var/mail directory exported. And lastly, it was a NFS server.On the mail server:Ensure attribute information is correct:# cd /var# ls -ld maildrwxrwxrwt 4 root mail 512 Jan 5 22:38 mailModify the dfstab file# cd /etc/dfs# vi dfstabshare -F nfs -o rw -d "mailbox directory" /var/mail:wq!# shareall# cd /etc/init.d# ./nfs.server startVerify /var/mail is shared.# dfsharesRESOURCE SERVER ACCESS TRANSPORT esoft:/var/mail esoft - -Setup mail client
More About: Mail , System , Unix , Server

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