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Installing MathabxInstalling Mathabx Mathabx is an important symbol library for latex. The full list of available symbols in latex can be found here. Following steps will help one to install mathabx in ...

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cronScheduled Tasks using cron Learn how to schedule tasks using cron in Linux!

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Using grep to find all files containing a text string in Linux

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Posted by Arsh | Labels: Linux, Ubuntu, Utilities | Posted on Friday, September 19, 2014

Often, we want to find if a directory structure contains a file with a given string pattern. This is specially useful for developers looking at a big code trying to connect various pieces of codes.

grep -rnw "STRING"  \path\ 

Here,

  • r is for recursive, n is for line number and w is for matching whole word.
  • STRING is the pattern one is looking for.  
  • replace \path\ by the directory you are searching in. Use '.' without quotes if it is the current directory.

Suppose, now one wants to find out if a certain string is present in certain file types only. Suppose we want to search for word php in .php and .xml files only. Then, we use a command like
grep -rnw --include=*.{php,xml} "php" .
--exclude is used to exclude certain file types or directories from the search in the similar fashion.

Warning! Failed to move file - Error Joomla Extension Manager

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Posted by Arsh | Labels: Joomla | Posted on Tuesday, May 27, 2014

If you are getting the following error - "Warning! Failed to move file" while trying to install an extension in the Extension Manager in Joomla! 3.x. Then it might be due to tmp directory write/ownership issue.


  • First make sure that tmp is writable. You can do that by Clicking System-->System Information-->File Permissions. If tmp is not writable, change permissions by chmod-ing permissions of tmp folder recursively to 777.
  • If tmp is writable, this issue could have been caused by ownership issue. The tmp folder might have been owned by FTP user and apache cannot write to it as you are trying to do in the extension manager. A simple fix is to delete the tmp folder and try to install the extension in the Extension Manager. If Apache can write to your home folder, it will create a tmp folder that Apache will own and installation of an extension will go through without a problem.
Hope this helps!

Using Ghostscript to concatenate two pdf files

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Posted by Arsh | Labels: Ghostscript, Linux | Posted on Monday, December 6, 2010

Install Ghostscript and use the following syntax -

gs -dBATCH -dNOPAUSE -q -sDEVICE=pdfwrite -sOutputFile=final.pdf file1.pdf file2.pdf

Extracting fields from multiple files using awk

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Posted by Arsh | Labels: awk, Linux | Posted on Sunday, February 7, 2010

Say, you have two files file1 and file2 containing data in the tabular form in 3 columns each and you want to extract column 2 of file1 and column 1 of file2. We can do it using the combination of paste and awk commands as follows:

paste file1 file2 | awk '{print $2 " " $4}'


We can do more! Suppose you want to add column 1 of file1 to column 3 of file2. This can be accomplished using the following command:

paste file1 file2 | awk '{print $1-$6}'

Installing Mathabx package for latex in Ubuntu

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Posted by Arsh | Labels: Latex, Linux, Mathabx, Ubuntu | Posted on Sunday, September 27, 2009

Mathabx is an important symbol library for latex. The full list of available symbols in latex can be found here. Following steps will help one to install mathabx in Ubuntu 9.04.

  1. Download mathabx.zip from the following link.
  2. $ unzip mathabx.zip
  3. $ cd mathabx
  4. $ sudo mkdir $TEXMF/fonts/source/public/mathabx
    In Ubuntu 9.04, TEXMF is /usr/share/texmf-texlive
  5. sudo cp source/*.mf $TEXMF/fonts/source/public/mathabx
  6. sudo cp texinputs/* $TEXMF/tex/generic/misc/
  7. Update the database
    $ sudo texconfig rehash
  8. Update the format file
    $ sudo fmtutil --refresh
  9. When you build your tex document, you might get an error that /Asterisk is defined again - To avoid that, comment the line in mathabx.dcl where /Asterisk is defined.
    $ sudo gedit $TEXMF/tex/generic/misc/mathabx.dcl
    Search for line where /Asterisk is present in mathabx.dcl and put a % sign at the start of the line.
  10. You are all set!

Scheduled Shutdown using cron

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Posted by Arsh | Labels: Ubuntu, Utilities | Posted on Thursday, May 14, 2009

Use the command
$ crontab -e
In the editor window write
0 9 * * * /sbin/shutdown -h now
This will shutdown your computer at 9 hrs. After this restart cron service:
sudo /etc/init.d/cron restart

Change file permissions recursively without affecting directories

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Posted by Arsh | Labels: Linux | Posted on Tuesday, May 12, 2009

If you want to change the permissions of the file to 600 without affecting the directories permissions, use the following command:

find . ! -type d -exec chmod 600 {} \;