For a system A to connect to a remote system B through SSH, A needs a SSH client (like PuTTY for Windows) and B needs a SSHD server running all the time so as to accept incoming connections.

SSH is a proprietary software offered by SSH Communications Security, and as an alternative the open source version OpenSSH is being widely used. On all Unix-based OSs, the OpenSSH SSHD server is installed by default during the installation of the operating system. On Windows, however, it is not the case.

You can install it on top of Cygwin very easily. You will need administrator access with a password set for the account. When you run the Cygwin setup to download or install various packages, select openssh which will select all the other packages it requires.

Once you complete the install, to configure SSHD run $ ssh-host-config –y from the terminal. This will automatically answer ‘yes’ for the yes/no questions. Give an appropriate password that follows your system rules if an sshd_server is being created or ignore this step. Specify the value of the environment variable CYGWIN as “ntsec tty” for WinXP and Vista and “binmode ntsec tty” for Windows 2003 Server (without quotes). At the end of this process, the sshd service will have automatically started and placed itself among the Windows startup list.

If you have any problems, try following this article for WinXP and Vista and this one for Windows 2003 Server or drop me a message.

Post from: EveryJoe

Installing and Configuring SSHD Server on Cygwin

Clean: Using CCleaner, I clean the PCs including all the browser caches and various other application caches. (Read my introduction to CCleaner here.)

Disk Cleanup: I run disk cleanup ($ leanmgr) on all the drives.

Registry: I run a registry cleaner (these days CCleaner itself) to clean the registries, after taking a backup of the current registry set.

Virus Scan: I run an entire PC scan, not just the scan across the “commonly infected areas”.

Defragment: Using the disk defrgamenter ($ defrag –a <drive>), I first analyze all the drives and if necessary defragment the recommended ones.

Updatedb: I update the Cygwin file index.

Backup: I take a backup of all important data on my Transcend Extensible Hard disk. A good idea, don’t you think?

Image Sources: CCleaner, Disk Cleanup and Disk Defragmenter.

Post from: EveryJoe

My Weekly Scheduled Jobs

One of the best things about Cygwin is that these commands useful for “quick and dirty” work on large chunks of text data are easy to learn, are consistent across all Unix-based OSs, have a number of options, and are quite extensive. When used in combination, they can save a lot of programming.

($ <command> <option> <inputs> is the general format for almost any of these commands. $ <command> –help shows the usage information.)

Note that all the commands below work on text files, not just any files with text content in them.  e.g. a .DOC or a .HTML contains many other headers which are also taken into account when processed by these commands.

wc: wc is short for “word count”, but it counts more than just words. It can count chars (-m), lines (-l) apart from words (-w).

uniq: When files have a large number of lines with many identical ones, uniq returns only once all lines among the input files after discarding repetitions. –c also gives the number of times each line has been repeated, –u returns only the unique lines discarding any line which has been repeated more than once, –i considers two lines non-unique if they are only differing the case.

sort: Say you have several files with numbers or words that need to be sorted. Sort can sort a concatenation of several files at once, where each line is considered a separate value to be sorted. The sorting order can be specified as in –d means dictionary-order, –f means ignore case, –n means numeric sort, –u means sort only unique lines.

grep: Short for “get regular expression”, grep can be used to search for a specific string or string pattern (called regular expression) in given text. $ grep “grep” <this-post> shows all the lines with the string “grep” in them. –c is used to count the number of occurrences, –i is used to ignore case, –v is used to invert the result.

sed: sed is used primarily to find and replace a string or string pattern from files. The most common usage is $ sed ‘s/<find-string>/<replace-with-string>/g’ which replaces all occurrences of <find-string> with <replace-with-string>.

Post from: EveryJoe

Cygwin Commands for Text Manipulation

find is one of the most useful commands when you also have to search within unknown files and make further operations on the result set. It does a recursive search, looking in all subdirectories.

The first set of arguments is always the paths where the search should initiate. $ find /home /tmp <remaining arguments> would search based on the remaining arguments in /home, /tmp and all their subdirectories. If unspecified, the default path is taken as ‘.’, the current working directory.

To search for a specific filename pattern, –name <regexp> is used as the next argument. $ find /home /tmp –name *.sh returns all .SH files present in /home, /tmp and their subdirectories.

Instead of piping, to perform any operation on each of the results returned, –exec is used. $ find /home /tmp –name *.sh –exec grep todo ‘{}’ \; –print searches for the string todo in the above returned files. grep does the search and ‘{}’ implies that all results need to be processed. The –print prints the final output, the actual lines containing the specified string in the files.

Instead of grep, it could be chmod or chown or any operation that can be done of files. These above options are the most common use cases of find.

There are a number of other options to refine the search like complex expressions with boolean operators, the maximum and minimum depth of subdirectories that need to be traversed, the modification times and permissions on files, the file types, etc. You can read about all these in the manual page.

Post from: EveryJoe

Google Your PC Using Find

IMHO, both Windows and Google Desktop Search consume too many resources.

e.g. Windows Desktop Search recommends Pentium 1 GHz Processor and 256 MB RAM, 500 MB of free hard disk space,… A process that starts automatically all the time. Note that we don’t search for files on our desktop all the time and mostly have an idea which file sits in which folder. A desktop search is for that occasion where we’ve “lost” some file, now and then.

Cygwin provides the best alternatives: locate and find.

locate coupled with updatedb helps you find any file (even hidden ones and those in temporary cache folders) in your system.

When you run the updatedb ($ updatedb), as the name suggests, it updates its database creating a simple index of all the files that are present in the system, with full paths. The first time you run it, like any other indexing application, it takes a few minutes to index the whole system. From the next time, it barely takes a minute, if you run it periodically, that is. I run updatedb about once every week to keep the index fresh.

After updating the file index, you can start using locate.

$ locate <substring-of-filename>

gives you all the files on your PC which contain the substring in their filenames, within a second. Even the files that accidentally got saved in some obscure temporary folder can be retrieved easily.

There are more options to update and locate files with extra preferences but I never had to use them much. The default usage suffices.

The great thing, apart from the speed of retrieval, is that this is not resource intensive and a dedicated process is not always running on your system for it. Of course, you need Cygwin installed.

Post from: EveryJoe

Locate: A Desktop Search Alternative

On this occasion, the super blog has two interesting posts: Our Best Posts From 2005 to 2009, and Weirdest and Most Controversial Posts.

I am especially thankful to Gina Trapani, the blog’s founding editor, for introducing me to Cygwin and the todo.sh. She used to make frequent posts but has been writing only a weekly column on the blog these days. She released a book, Upgrade Your Life: The Lifehacker Guide to Working Smarter, Faster, Better, which consists of all the best hacks from Lifehacker.com’s archives, and her personal manifesto on working more efficiently in the digital age. Check out the official web site of Upgrade Your Life to browse the table of contents and download a sample chapter.

Happy birthday, Lifehacker! Many happy returns of the day. I am a regular visitor of Lifehacker, a big user of Cygwin, and I hope that the four-hour-long course that I did today on time management nudges me enough to become a daily user of todo.sh.

In this spirit, dear readers, here is the ultimate list of free Windows software from Microsoft. Enjoy.

Post from: EveryJoe

Happy Birthday Lifehacker

Directory Structure
Cygwin uses the POSIX notation standard in paths. That is, instead of ‘\’ as in Windows, it uses the more convenient ‘/’ as in Unix. The web follows the same notation. For instance, take http://thatdamnpc.com/category/cygwin-unix. On the web host, one might find a directory called “category” in the main directory and a sub-directory “cygwin-unix” along with other category names in it.

‘/’, the root directory, is considered the parent directory under which all directories fall, like /usr, /bin, /lib, /tmp, /var, etc. /A/B/C/D/E/F.txt would mean a file F.txt present in E, a sub-directory of D, which is a sub-directory of C, which is a sub-directory of B, which is a sub-directory of A, which is a sub-directory of /, the root.

If you look at the contents of / (ls / or dir /) in your Cygwin terminal, you will notice a sub-directory called cygdrive. This contains all the Windows drives in it. Your C: drive can be got to through /cygdrive/c.

For convenience, we can remove this /cygdrive prefix in the following ways:

1. $ cd /
    $ mkdir c e
    $ mount c: /c
    $ mount e: /e

2. $ mount –c /

In this way your main Windows drives will be direct sub-directories of /.

PATH
Check what your path is using echo $PATH command. It should have at least the following: /usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/c/WINDOWS/
system32:/c/WINDOWS:/c/WINDOWS/System32/Wbem:/c/SysinternalsSuite

Using this path setting, we can run even those programs that we could run from the MS Command Prompt. If you have any other files which can be run from command line, add them to the path using your .profile. We’ve already seen that.

Good to go from next week.

Post from: EveryJoe

POSIX and PATH

Poderosa is the best terminal emulator for Cygwin that I have come across. It has a tabbed GUI, much like the PuTTY Connection Manager. However, in addition to the network communication protocols through which one can connect to a remote system using PuTTY, local Cygwin shells can also be opened using Poderosa. I use it mainly for the latter purpose.

Poderosa allows the user to set custom fonts and colors, keyboard shortcuts, command suggestions, etc. The “detailed preference editor” is especially useful, though not very straightforward to use. The app was built in a plug-in architecture and allows one to build custom plug-ins.

Poderosa too needs .NET Framework 2.0 preinstalled on your computer. Unlike PuTTY Connection Manager, I found Poderosa very stable. For telnet though, Poderosa gave me trouble where the PuTTY Connection Manager worked.

Poderosa, according to the website, had funding from the Japanese Govt. during 2005. Presently, its development seems to have stopped over a couple of years ago. The last release was v4.1.0 and you can get it from here.

Image Source: Poderosa on my PC.

Post from: EveryJoe

Poderosa: The Terminal Emulator