Toybox | Technology Tales

A quick way to create a blank text file

27^th June 2008

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.

Using SAS FILENAME statement to extract directory file listings into SAS

30^th May 2007

The filename statement's pipe option allows you to direct the output of operating system commands into SAS for further processing. Usefully, the Windows dir command (with its /s switch) and the UNIX and Linux equivalent ls allow you to get a file listing into SAS. For example, here's how you extract the list of files in your UNIX or Linux home directory into SAS:

filename DIRLIST pipe 'ls ~';
data dirlist;
    length filename $200;
    infile dirlist length=reclen;
    input buffer $varying200. reclen;
run;

Using the ftp option on the filename statement allows you to get a list of the files in a directory on a remote server, even one with a different operating system to that used on the client (PC or server), very useful for cases where cross-platform systems are involved. Here's some example code:

filename dirlist ftp ' ' ls user='user' host='host' prompt;
data _null_;
    length filename $200;
    infile dirlist length=reclen;
    input buffer $varying200. reclen;
run;

The PROMPT option will cause SAS to ask you for a password, and the null string is where you would otherwise specify the name of a file.