Tag Archive for UNIX

Ghostscript: **** Unable to open the initial device, quitting.

October 6, 2008 No comments

The above error message has been greeting me when creating PDF’s with Ghostscript on a Solaris box and does need some translation. If you are directing output to a real printer, I suppose that it is sensible enough: nothing will happen unless you can connect to it. It gets a little less obvious for PDF creation and seems to mean that the pdfwrite virtual device is unable to create the specified output file. A first port of call would be check that you can write to the directory where you are putting the new PDF file. In my case, there seems to be another cause so I’ll have to keep looking for a solution.

Update: I have since discovered the cause of this: a now defunct TEMP assignment in the .profile file for my user account. Removing that piece of code resolved the problem.

Linux, Software, UNIX, Windows

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A way to combine PDF files in UNIX and Linux

October 4, 2008 2 comments

My latest adventure in the world computing has led me into the world of automated PDF generation. When my first approach didn’t prove to be completely trouble-free, I decided to look at the idea of going part of the way with it and finishing off the job with the open source utility Ghostscript. It is that which got me thinking about combining bookmarked PDF files and I can say that Ghostscript is capable of producing what I need as long it doesn’t generate any errors along the way. Here’s the command that does the trick:

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=final.pdf source_file1.pdf source_file2.pdf

The various switches of the gs command have very useful roles with dBATCH ensuring that Ghostscript shuts down when all is done, dNOPAUSE removing any prompts that would otherwise be given, q for quiet mode, sDEVICE using Ghostscript’s own PDF creation functionality and sOutputFile creates the output file, stopping Ghostscript from sending it to its default stream. All of this applies to Windows Ghostscript too, though the name of the executable is gswin32c for 32-bit Windows instead of gs.

When it comes to any debugging, it is useful to consider that Ghostscript is case sensitive with its command line switches, something that I seen to trip up others. I am getting initial device initialisation so it strikes me that dropping some of the ones that reduce the number of messages might help me work out what’s going on. It’s a useful idea that I have yet to try.

There is also online documentation if you fancy learning more and Linux.com have an article that considers other possible PDF combination tools as well. All in all, it’s nice to have command line tools to do these sorts of things rather than having to use GUI applications all of the time.

Linux, Software, UNIX, Windows

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Recursive FTP with the command line

August 6, 2008 No comments

Here’s a piece of Linux/UNIX shell scripting code that will do a recursive FTP refresh of a website for you:

lftp <<~/Tmp/log_file.tmp 2>>~/Tmp/log_file.tmp

open ${HOSTNAME}

user ${USER} ${PSSWD}

mirror -R -vvv “${REP_SRC}” “${REP_DEST}”

EndFTP

When my normal FTP scripting approach left me with a broken WordPress installation and an invalid ticket in the project’s TRAC system that I had to close, I turned to looking for a more robust way of achieving the website updates and that’s what led me to seek out the options available for FTP transfers that explicitly involve directory recursion. The key pieces in the code above are the use of lftp in place of ftp, my more usual tool for the job, and the invocation of the mirror command that comes with lftp. The -R switch ensures that file transfer is from local to remote (vice versa is the default) and -vvv turns on maximum verbosity, a very useful thing when you find that it takes longer than more usual means. It’s all much slicker than writing your own script to do the back-work of ploughing through the directory structure and ensuring that the recursive transfers take place. Saying that, it is possible to have a one line variant of the above but the way that I have set things up might be more familiar to users of ftp.

Linux, UNIX, Web Tools

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How much space is that folder taking up on your disk?

July 23, 2008 No comments

In Windows, it’s a matter of right-clicking on the folder and looking in its properties. I am sure that there is a better way of doing it in that ever pervasive operating system but, in the worlds of Linux and UNIX, the command line comes to the rescue as it is wont to do. What follows is the command that I use:

du -sh foldername

The s option makes it present the total space taken up and leaving it out gets you a breakdown of how much space the subfolders are taking up as well. The h makes the sizes output more friendly to human eyes with things like 10K, 79M and 51G littering what you get. The command itself is a much shorter way of saying “print disk usage”. It’s all quick and easy when you know it and very useful in this age of ever increasing data volumes.

Linux, UNIX, Windows

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A quick way to create a blank text file

June 27, 2008 No comments

The primary job done by the touch command in UNIX or Linux is to update the time stamps on files. However, it also has another function: creating an empty text file where you are "touching" a file that doesn’t exist. This has its uses, particularly when you want to reduce the amount of pointing and clicking that you need to do or you want to generate a series of empty files in a shell script. Whatever you do with it is up to you.

Linux, UNIX

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Quickly surveying free disk space on UNIX and Linux

June 21, 2008 No comments

Keeping an eye on disk space on a Solaris server is important for me at work while keeping the same top level overview is good for my use of Linux at home too. Luckily, there’s a simple command that delivers the goods:

df -h 2>/dev/null

The "df -h" piece is what delivers the statistics while the "2>/dev/null" rids the terminal of any error messages; ones stating that access has been denied are common and can cloud the picture.

Linux, UNIX

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