• Good shell comparison including variable expansion - hyperpolyglot.org
• Shell coding standards - opengroup.org
• aix4admins
• The Deep, Dark Secrets of Bash
• Korn Shell Functions
• AWK reference from Bruce Barnett
• HANDY AWK ONE-LINERS
• Unix quoting from from Bruce Barnett (grymoire)
• Another excellent quoting tutorial
• AIX snapshot technology
• RaspberryPi
• SSH
• Screen sharing from Unix using screen
• Screen sharing from Unix using tmux
• Handy ex and vi reference
• Fedora install for my own purposes

• maildrop
• Using maildrop As A Mail Delivery Agent (MDA)
• .mailfilter examples
• Setting up fetchmail with Gmail
• Using Fetchmail to Retrieve Email

Eventually, after months of trying different things, came up with this combination of tools that worked very well.

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• Set Gmail account up for POP and disable IMAP

This is the part that talks to Gmail and downloads the emails to the local machine.

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If fetchmail complains about ssl certificates, try specifying wherein is with the sslcertfile line

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Not really sure why this filter is not working properly. The cc works but the To: check doesn't. So I have a shell that runs separately to process the emails in the backup mail directory.

This is a clever program that can extract attachments from emails and put them in a directory of you choosing.<br /> This shell runs from cron at regular intervals to run the whole process

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echo an '=' sign then use the loop feature of sed to run round a loop a further 79 times replacing what you've got with the same thing plus and extra one!

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This way should be portable and give predictable results

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Actually deceptively simple. Example remove the header from df output.

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As a useful extension, suppose TO_DATA_DIR contains multiple directories, this will total the free space for all relevant filesystems<br /> This one is specific to AIX, for other Unixes and Linux, use $4 instead of $3.

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• delete comment lines
• delete all lines after the one starting with a semicolon
• delete all blank lines
• change reuse to set
• change archivelog (with word boundaries) to noarchivelog
• change old sid to new sid

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Mostly we want to search for files containing a particular string but how to find those files that do not contain some text.<br /> Using xargs instead of -exec forces the filename to be printed. -H should do this but doesn't seem to in this case.

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From the destination server, this will connect to the source, tar up each file and pull it back to the current server

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# - trims everything from the start of line till the FIRST occurrence of following character (abstemious) <br /> ## - trims everything from the start of line till the LAST occurrence of following character (greedy)<br /> % - trims everything from the end of line backwards till the FIRST occurrence of following character (abstemious)<br /> - trims everything from the end of line backwards till the LAST occurrence of following character (greedy) <code>11@@</code> or<br /> <nowiki>#</nowiki> - remove prefix reluctantly<br /> <nowiki>##</nowiki> - remove prefix greedily<br /> % - remove suffix reluctantly<br /> - remove suffix greedily<br />

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It was written by someone at Oracle. Unfortunately (s)he did not put any author comment in it. Also unfortunately I cannot show it here as it is protected behind Oracles support website.<br /> If you have an Oracle Metalink id, you can get the complete script here<br /> Here is a snippet of a function that demonstrates proper commenting and a very good style.<br > The script is called physru.sh and upgrades an Oracle database in a rolling upgrade fashion by using a physical standby.<br /> There are 4500 lines in the full script but it is so easy to read and understand because of the way it's written, it's like a breath of fresh air. Well done whoever you are!

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Doesn't work in Korn shell due to %*s

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and as a one-liner

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This works in Korn shell…

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Sometimes have problems with NFS mounts and this causes cron jobs to hang. If they are scheduled to run regularly, eventually cron will no longer be able to start any more jobs.<br />

• Check the cron log /var/adm/cron/log to see if there are any errors or other messages around the time the jobs should run.

If cron has hit its process limit (default 100), it will try again after a number of seconds (default 60).<br /> Both the number of jobs and wait time are configured in the file /var/adm/cron/queuedefs. If it is unusual for cron to be running so many jobs, you can check the process table to view the jobs cron has created. These jobs will have parent process id (PPID) of the cron daemon.<br />

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In this example, we only have 1 job running

Processes running longer than 24 hours have a date instead of a start time…

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Borrowed from Mozilla Firefox installer

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Put something like this in the .profile<br /> -n do not output the trailing newline<br /> -e enable interpretation of backslash escapes<br />

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or as part of a script that removes comments and blank lines from all Korn shell scripts in a directory

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From here<br /> Could be used to separate the columns of an SQL select when returning to the shell<br /> This approach eliminates the need to put quotes around text with spaces in it.

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pipe the calculation into the shell calculator

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Calculate the remainder (modulo) of a division calculation

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or do it in awk if scientific notation maybe involved

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Encrypt a shell script with the ability to execute the encrypted version

• from commandlinefu.com

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and in /etc/hosts, add…

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Redhat/CentOS

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Debian

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then…

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In man's terms, that last line would translate to:

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Mac OSX

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This will run a job every 5 minutes and send the output to a file ending with a time in hours and minutes.<br /> The thing to note is the escaped percent signs. This is because a % sign is interpreted by cron to mean a newline character. Everything after the first % is treated as input to the program.

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It can happen that you need to add or modify a line in the crontab of many users or across many servers at once.<br /> In principle, there's nothing wrong with modifying the crontab file directly. You just lose the advantages of file locking (and syntax checking) that crontab -e offers.<br /> Here we take a backup of the current crontab, print it out, echo an extra command and ask cron to use these as input (thus overwriting the existing crontab file). Just don't run this close to midnight

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or

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or

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Run from the management server across all Unix servers. Checks the 5th column in a ps listing. If it doesn't find a : (time separator), the process is running longer than 24 hours.

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Example. Execute a job every third Saturday of the month.<br /> Paste this into a file called calenday and put it in /usr/local/bin so it's (probably) on the PATH

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Now in crontab, you should be able to do something like this:<br />

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This will also work on some Unices..<br /> We send backups to a special TSM node on the second Friday of each month. This report must run a day later - but that is not guaranteed to be the second Saturday or even the 3rd. So…

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But you can see elapsed time using your own ps command

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This shows all the individual arguments to the command

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This shows the ps listing in 'compatibility' mode (there are more compatibility commands in /usr/xpg4/bin)

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This shows the full argument listing of a process (NOTE: no minus sign!)

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Maybe you cut and pasted a file from Windows and it's full of blank lines and Control-M's now<br /> There are several methods but I think this is the easiest to remember

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a function like rpad in SQL but for Shell<br />

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My remmina stopped working so rolled my own. Very simple really. Put this is a shell.

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Slight problems with rdesktop not working 100% of the time. Now using xfreerdp. Seems better…

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must be done as root

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It'll check to see if the sum of filesizes corresponds with the df -g (or h) listing (can get messed up due to open but deleted files)

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• AIX

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• Solaris

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• Linux

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• RRDTool

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or “How to send shell output to screen/stdout as well as to a logfile using tee and redirection with exec”<br /> <br /> examples here on unix.com

• general info on redirections here at catonmat.net

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found here on stackoverflow

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• How to fix read only root file system

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Checks if resource group is on this leg of an HACMP cluster. Returns 0 if true else 1.

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Use awk instead

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this prints the last word of the second line in the paragraph in dsm.sys that contains the search term AGRHDWQ1.<br /> Or slightly simpler…

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or, case insensitively:

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Using -v means you don't have to use a BEGIN section.

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or

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or

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or

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cd diag and repeat until culprits are found

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Not as easy as it sounds if it needs to work in non-ksh93 shells

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or maybe more neatly done in Perl…<br /> This will capitalise each word in a sentence passed into it

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Use ls with -i to see inode listing

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Use find with -inum to get the filename and -exec to remove it

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Doing it this way means we do not need to scp the shell over to the host before executing it!

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First of all, this command is a redirection: your shell will open the file your_script.sh and feed it as input to the ssh command. ssh, in turn, will tunnel its stdin to the remote command, namely, sh instance. And sh without arguments reads its script from stdin. So we got sh instance, which is launched on remote host, but reads commands from your local file.

This is the way I wanted to do it but there's an issue. Where does that spare } character come from? Anyone?

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ps listing

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Results of above command

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Workaround 1. Send the ps listing to a file and work on it without pipes. Works but it's a bit long-winded especially as we have to clean up afterwards.

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Workaround 2. Don't like the grep -v but until I find out where that } is coming from..

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Using an exit status from SQL*Plus back to the shell so we can decide what to do. Nice one!

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These methods have the advantage of allowing arguments of any length not just 1 character

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another way - found in /etc/init.d/functions (daemon function) in Fedora

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another way - found in adstrtal.sh (middleware start script for EBS)

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and another in adautocfg.sh

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to be investigated… this one might be cleverer than mine…

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improved version…<br /> just escape double quotes and dollar signs…

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basename $0 does not always give the desired answer (might give “./”!

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Also see Distribute files to multiple servers using rsync and ssh

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Strip out comments and blank lines from a file

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Does a ps and a grep

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Getting a decent listing of filesystem space available. It is ordered such that the filesystems with no space left are at the end.

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A handy way of listing subdirectories and their files

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Watch progress of a copy

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Reboots Linksys router

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Nice one for bash. Colour codes the prompt depending on the outcome of the previous command

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Mmmm, to be looked into. Executes remote commands on a unix box using curl.

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• unixpeople.com

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then just connect using

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From grymoire.com

From dartmouth.edu Reproduced here just in case it disappears! Advanced shell scripting

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Ping to an IP address works ping 74.125.136.103 but this doesn't ping www.google.com

Check resolv.conf cat /etc/resolv.conf nameserver 95.130.132.17 nameserver 95.130.132.18 I had changed internet provider and forgot to update this. Just to set it to the router address and let that do the resolution nameserver 192.168.1.1

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Mmm. See our output and also tee it to a log file!

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Ref: http://www.cyberciti.biz/faq/kvm-virtualization-in-redhat-centos-scientific-linux-6/<br /> Build an empty space for a CentOS virtual machine

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Tried creating image with

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gives error

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Package will not work if dependencies are required

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Use package name (as seen in -qi above), not full name

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Compares information of installed files of the package against the rpm database

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• Download rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm
• Import the key

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• Install the repository

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• Check the installation

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• Test it

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Checkout this file for global yum config

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You need to download the yum .repo file from the server, as per the steps below. After this, you need to enable a flag in the .repo file as per your operating system version. Having done these two steps, when you run yum install <pkgname> command on your linux box, the Oracle's yum server will be scanned, the dependent & the relevant rpm's will be download and installed for you.<br /> cd /etc/yum.repos.d To download files here wget http://public-yum.oracle.com/public-yum-el5.repo

A file named public-yum-el5.repo will be created in your directory<br /> Edit this file and enter enabled=1 against the operating systems which is relevant to you vi public-yum-el5.repo

Next run the yum command yum install package-name

As root:

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replace the line “iface eth0 inet dhcp” with

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You should also take a look at the file /etc/resolv.conf and check it has a nameserver entry (probably pointing at your default gateway) or direct to your ISP name servers.

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• connect to wifi network from command-line in linux - from blackmoreops.com

Short summary of all the things you need to do in just few lines

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As root:

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Resrart the network interface

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Check name server entry in resolv.conf

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This is a damn fine AIX utility - part of the CSM Distributed Shell. dsh -a “ls -al /etc/apache2/*conf” will list the Apache configuration file on all reachable servers (nodes)

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Been looking for this for a long time.<br /> You can put:

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in your .profile but this will be ruined if you do a copy/paste into another file.<br /> I wanted a way of doing this without entering the control character in the .profile. Finally stumbled upon it. And it's so simple. Just escape the caret!

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Put this in the .profile. It's copy/pastable and it works!<br /> If you want CTRL-H to be your erase character, just do this:

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The -g option of stty gives a compact list of all the settings or the terminal and can be used as input to stty

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If you've done a cat of a binary file or something else weird and your terminal is left in a mess, the following key sequence should bring it back to normal

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Download Package

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Change to root

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Remove the old stuff

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Extract Package

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Install Package and exit root

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Start it

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or

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From Bruce Barnett

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