Added article about pax(1)

and fixed a typo in roff

rocks/computers/software/pax.md

@@ -0,0 +1,32 @@
+# pax(1) is a well done tar(1)
+
+pax(1) allows you to create .tar files in a UNIX way:
+
+~~~
+# create a tar file of a directory
+pax -w directory > directory.tar
+# see the contents of a tar file
+pax < directory.tar
+# extract contents
+pax -r < directory.tar
+# create a compressed tar file
+pax -w directory | gzip > directory.tar.gz
+# decompress a file
+zcat directory.tar.gz | pax -r
+~~~
+
+These are tar files, so they're compatible with tar(1)
+
+You can also use pax(1) in a cringe, non UNIX way:
+
+
+~~~
+# create a .tar file
+pax -w -f dir.tar dir
+# create a compressed file
+pax -zw -f dir.tar.gz dir
+# decompress a file
+pax -zr -f dir.tar.gz
+~~~
+
+(I think you get the point)

rocks/computers/software/roff.md

@@ -61,7 +61,7 @@ a sup 2 over 2
 .EN
 .EQ
 x = {
-b +- sqrt {-b sup 2 * 4ac}
+b +- sqrt {-b sup 2 - 4ac}
 } over 2a
 .EN