Programming Note

Emacs is a classic editor in Linux/Unix world. However, it can also run on Windows. For Windows users, ntemacs is a good choice. What I don’t like is: Emacs needs the environment variable “HOME”, and it looks for its configure file “_emacs” in the “HOME” directory. I don’t like setting environment variables because it may cause conflicts. If there is a method so that I needn’t set any environment variable, I can avoid this problem. Lukily, I found the solution: Windows script. (more…)

This is a very short note for “gzip”. “gzip” is a standard compress utility in Linux operating system. It can compress a file. Unlike WinRAR or WinZip in Windows, gzip isn’t suitable for creating an archive files which contains many files and directories (this is “tar” task).

To compress a file, e.g. foo.txt, use ‘gzip foo.txt’. It will generate a file whose name is foo.txt.gz. However, the original file, foo.txt, will be removed. To uncompress a gzip file, use ‘gunzip’. e.g. after executing ‘gunzip foo.txt.gz’, the ‘foo.txt.gz’ will be replaced by ‘foo.txt’.

Sometimes I don’t hope gzip delete my original file. For example, if I have a file named “foo.img” and I want to backup it. I can use the argument “-c”:
gzip -c foo.img > foo.img.gz

Here, “-c” means put the compressed file to the stand output device, normally it is the screen. Then I use a redirect symbol “>” to specify the output file. In this way, the original file won’t be deleted.