Editing Guide to RSF file format (section)

===Datapath===
How did the RSF program (<tt>sfmath</tt>) decide where to put the data file?
In the order of priority, the rules for selecting the data file name and the
data file directory are as follows:
  
#Check <tt>--out=</tt> parameter on the command line. The parameter specifies the output data file location explicitly. 
#Specify the path and the file name separately.    
#*The rules for the path selection are:   
#*#Check <tt>datapath=</tt> parameter on the command line. The parameter specifies a string to prepend to the file name. The string may contain the file directory. 
#*#Check <tt>DATAPATH</tt> environmental variable. It has the same meaning as the parameter specified with <tt>datapath=</tt>. 
#*#Check for <tt>.datapath</tt> file in the current directory. The file may contain a line  <pre> datapath=/path/to_file/ </pre> or <pre> machine_name datapath=/path/to_file/ </pre> if you intend to use different paths on different platforms. 
#*#Check for <tt>.datapath</tt> file in the user's home directory. 
#*#Put the data file in the current directory (similar to <tt>datapath=./</tt>). 
#*: 
#*The rules for the filename selection are:   
#*#If the output RSF file is in the current directory, the name of the data file is made by appending \@. 
#*#If the output file is not in the current directory or is created temporarily by a program, the name is made by appending random characters to the program's name and selected to be unique. 

Examples:

<pre>
bash$ sfspike n1=10 --out=test1 > spike.rsf 
bash$ grep in spike.rsf         
in="test1" 
</pre> 

<pre>
bash$ sfspike n1=10 datapath=/tmp/ > spike.rsf 
bash$ grep in spike.rsf         
in="/tmp/spike.rsf@" 
</pre> 

<pre>
bash$ DATAPATH=/tmp/ sfspike n1=10 > spike.rsf 
bash$ grep in spike.rsf         
in="/tmp/spike.rsf@" 
</pre> 

<pre>
bash$ sfspike n1=10 datapath=/tmp/ > /tmp/spike.rsf 
bash$ grep in /tmp/spike.rsf 
in="/tmp/sfspikejcARVf" 
</pre> 

====Packing header and data together====
While the header and data files are separated by default, it is also possible
to pack them together into one file. To do that, specify the program's
"<tt>--out</tt>" parameter as <tt>--out=stdout</tt>. Example:
<pre>
bash$ sfspike n1=10 --out=stdout > spike.rsf
bash$ grep in spike.rsf
Binary file spike.rsf matches
bash$ sfin spike.rsf
spike.rsf:
    in="stdin"
    esize=4 type=float form=native
    n1=10          d1=0.004       o1=0          label1="Time" unit1="s"
        10 elements 40 bytes
bash$ ls -l spike.rsf
-rw-r--r--  1 sergey users 196 2004-11-10 21:39 spike.rsf
</pre>
If you examine the contents of <tt>spike.rsf</tt>, you will find that it
starts with the text header information, followed by special
symbols, followed by binary data. 
Packing headers and data together may not be a good idea for data processing, but it works well for storing data: it is easier to move the packed file
around than to move two different files (header and binary) together while
remembering to preserve their connection. Packing the header and data together is also the current mechanism used to push RSF files through Unix pipes.