Going MAD

Moving Around Directories
Just like when in the shell, once you have started your picolisp process you may want to traverse the directories and get other information.
This is easy enough to accomplish with just a few functions.
Notice that all the below functions return either a string or a list of strings. Strings are otherwise know as Transient Symbols in picolisp.

(pwd)
-> "/home/vid"
So simple! and it tells you your current working directory, cwd. A good Mnemonic to help you remember this command is print working directory, pwd.

(dir "dirname" flg)
-> ("myDir" "someFile.txt" "myOtherDir")
"dirname" defaults to your cwd and you can set flg to True to get hidden files too.
if you supply a filename instead of a directory you get NIL. This is somewhat true of all picolisp functions. You mostly get NIL results for failures.

(cd "/some/new/path")
-> "my/current/directory"
you can cd into any directory just like in the shell.
The return value is your cwd and NIL if you gave a non existing directory.

(chdir "dir-path" Prgs)

(chdir ".." (cd "..") (dir))
-> ("Public" "Dropbox" "picoLisp" "News" "wiki" "electric.log" "2016-01-07 10.40.55.jpg" "Documents")
If you just want to temporarily move directories and get something done and restore back to the current directory, use chdir.
In the above examples Prgs just means 1 or mores lists.

So the second call,
(chdir ".." (cd "..") (dir) just means, chdir backwards, cd backwards again, then list directory (dir), and finally restore back to the cwd.

(dirname "some/file")
-> "some/"
(basename "some/file")
-> "file"
if you finally got the path to your file, you can get the path and filename with dirname and basname.

http://thevikidtruth.com/5000/?filesanddirectories

18may16   admin