remove zero sized file

To delete zero sized files in bash you can simply use an if clause with you can put in a loop. First the if clause

  if [ ! -s file ] ; then
    rm file
 fi

and finally the full loop:

 for file in *
 do
   if [ ! -s $file ] ; then
     rm $file
   fi
 done

Bash combining files

Combine files side by side columnwise:

If you have two files one of them consisting of one column and another file consisting of one column as well you can join the files by using:

paste file1 file2

Combine files one after the other:

Simply use:

cat file1 file2

which will first print file1 and then file2.

The "join" command:

Additionally there is also the join command which will print data which is present in file1 and file2, e.g.:

join file1 file2

If file1 and file2 share the same string in one line it gets printed to standard out.

Periodically execute program (bash) - watch

To periodically execute a command, e.g. ll to see the change in files just use watch:

watch  [-n <seconds>] [--differences[=cumulative]] [--interval=<seconds>] <command>

For example like this:

 watch ls -l

Gnuplot write in a variable from bash

If you want to read in a variable, which is in a file for example or you simply have a script to calculate it into gnuplot. Simply use the following command:

 variable="`BASH COMMAND`"

instead of BASH COMMAND you can use any bash command you like and even load variables or get data from files, e.g.:

 variable="`echo $VARIABLE`"

bash "--" = no more options

This one is a bash tweak! If you need to tell a bash script, that there are no more options to come you can just add -- after all comments.
This is especially helpfull if a keyword after that has to start with a minus.

 rename -- -help help *  

renames the -help into help in all files.

Hi

Hi,

I am a graduate student in the field of theoretical chemistry and with this blog I mostly just want to remember all the hacks I did for Gnuplot, Latex and all the other scripting languages I use.

Additionally I probably will put up a few setup files for gnuplot, latex, vmd, emacs and so on.

So if you are interested in that keep on looking =)

Best,

Koni