Unix file systems are the hierarchical.
All file systems together make up the tree.
All devices are files, for example

       /dev/rmt/0lbn     - is the tape,
       /dev/dsk/c0t2d3s2 - is the disk partition
       /dev/null         - empty device,
       you can redirect all garbage to this device

All file systems starting from root "/".
Note, that UNIX uses the regular slash "/"
instead of DOS's back slash "\".

To get a disk report use the "disk free" command
df -k , where k means kbytes. Here the result example:
 


Filesystem            kbytes    used     avail   capacity  Mounted on
/dev/dsk/c0t2d0s0      48023   23400     19823       55%    /
/dev/dsk/c0t2d0s3     327711  250346     44595       85%    /usr
/proc                   0        0         0          0%    /proc
fd                      0        0         0          0%    /dev/fd
swap                  165816    32       165784       1%    /tmp
/dev/dsk/c0t2d0s4     433639  332821     57458       86%    /opt
/dev/dsk/c0t1d0s7    1967118 1692863     77545       96%    /export

File names convention:
File name does not contain metacharacters of shell  such as &,  < ,  >,  ;  *, $
File maximal name length is less than 256.
Examples of file name extensions:

    c-file "filename.c",
    header file "filename.h",
    object file "filename.o",
    a.out    -  executable standard file name
 

A Shell is the command intepretator that
executes commands from a terminal or a file. There are
some popular shells:
       sh,  csh,   tcsh,  ksh,  bash
 


 sh            - Bourne shell, it's the standard shell
 csh           - C-shell, one of more popular shells,
 tcsh          - GNU extended version of csh
 ksh           - Korn shell
 bash          - Bourne again sh,
                 extended version of sh.

Environment variables are variables that are defined
per given shell, for example:

 HOME          - home directory name for given shell
 PATH          - path collection for given shell
 MANPATH       - collection for on-line manulals
 DISPLAY        - IP address for given host and him display
               and many others.

 env, printenv - show environment variables

Commands using shell history:

 !pattern      -  run last command starting with "pattern"
 !!            -  run  last command
 !!:p          -  only show last command
 !!:s/old/new  =  ^old^new
 ls !$         -  get last argument from the last command

tcsh line commands :

 ^a            -  go to beginning of a line
 ^e            -  go to end of a line
 ^d            -  previous command
 ^n            -  next command
 ^k            -  erase to end of line and more
 ^u            -  erase a line

Unix command	DOS equivalent	 Description
ls	        dir	         List directory
pwd	                         Print working directory
cd	        cd	         Change directory
cp	        copy	         Copy file
rm	        del	         Remove (delete) file
mv	        rename           Move (rename) file
mkdir	        mkdir            Make (create) directory
rmdir	        rmdir            Remove (delete) directory
cat	        type	         Concatenate (display) file
more	        type	         Display file by pages
man	        help	         Man pages (help)

ls -l     permissions, owner, group, number of bytes, date, ...

See result example:
total 1808
drwxr-xr-x   2 rafael   daps      1024   Nov  25    15:57   Save-24-Nov-97/
drwxr-xr-x   2 rafael   daps       512   Jan   9    1997    Scenarios/
-rwxr-xr-x   1 rafael   daps      6436   Nov  19    15:04   a.out*
-rw-r--r--   1 rafael   daps      1173   Nov   4    16:26   changes_to_1.5.5
-r--r--r--   1 rafael   daps      3927   Nov  26    16:51   communication.c
-r--r--r--   1 rafael   daps     13698   Sep  28    10:03   dbs_sender.c
-rw-r--r--   1 rafael   daps     30136   Nov   3    20:25   diff_ev
............

ls -a                 show hidden files

See result example:
./                     Mail/
../                    Packages/
.Xauthority            SYBASE_1
.Xdefaults             Top/
.alias.own             ccc
.app-defaults/         ccmail/
.cshrc                 conf1.gif


 ls -tl      -  show all files sorted by time

              Copy files
 cp                        -   copy files
 cp f1 f2                  -   copy file "f1" to file "f2"
 cp -i  f1  f2             -   copy with confirmation
 cp f1 f2 f3  /dirname     -   copy files "f1", "f2", "f3" to /dirname
 cp  *.c   /dirname        -   copy all files *.c  to /dirname
 cp -r   dir1  dir2        -   recursive copy directory dir1 dir2

              Move  files
 mv                        -   move files
 mv  f1 f2                 -   rename file "f1" to file "f2"
 mv  -i f1 f2              -   rename with confirmation
 mv  f1 f2 f3   /dirname   -   move files "f1", "f2", "f3" to /dirname
 mv  *.h  /dirname         -   move all files *.h to /dirname

 mkdir   "dirname"         -   make directory
 rmdir   "dirname"         -   remove directory
 rm -r   "dirname"         -   recursively remove directory
 du -s                     -   show disk usage ( in blocks )
 du -k                     -   show disk usage ( in kbytes )

  man  "keyword"           -  display manual pages about "keyword"
  man  -k "keyword"        -  show summaries from index  index database
  man  -s 2 "keyword"      -  display chapter 2 about "keyword"