Advanced Oracle Utilities: The Definitive Reference by Rampant TechPress is written by the top Oracle database experts (Bert Scalzo, Donald Burleson, and Steve Callan).  The following is an excerpt from the book.

The UNIX pwd command

The pwd command is probably the most commonly used UNIX command.  It is short for Print Working Directory, and it tells where the DBA is located in the UNIX tree structure.  For example, issue the pwd command to see the current directory:

 root>pwd
/export/home/oracle

The pwd command is very important, and many Oracle DBAs and UNIX system administrators place the output of the pwd command in their command prompt so they always know their current directory.  This is done by setting the UNIX PS1 system variable:

 PS1="
`hostname`*\${ORACLE_SID}-\${PWD}
>"
export PS1

With this setting, the UNIX prompt will change to always show the hostname, the $ORACLE_SID and the current working directory:

cheops*testsid-/u01/app/oracle/admin/testsid/pfile
>pwd
/u01/app/oracle/admin/testsid/pfile

The UNIX ls command

Another very frequently used UNIX command is the ls command.  Without any arguments, the ls command will show a list of all files in the current directory:

root> ls

Mailbox                   invalid.sql               run_rpt.ksh              
ad.sql                    kill_oracle_sessions.ksh  run_trunc.lst            
adamf_techeops             l.ksh                     run_trunc.sql            
admin                     list.lst                  schools.dmp              
afiedt.buf                list2.lst                 scripts                  
arsd.dmp                  lockee.txt                sql                       
bksel.lst                 lst.lst                   sqlnet.log

When the –a and –l arguments are added, all of the details for each file in the current working directory are shown:

root> ls –al

total 928188

drwxr-xr-x  21 oracle   dba         2048 Aug 22 20:47 .
drwxr-xr-x  10 root     root         512 Jul 26 08:49 ..
-rw-------   1 oracle   qmail        437 Aug 12 20:43 .bash_history
drwxr-xr-x  11 oracle   qmail        512 Sep  3  2000 .dt
-rwxr-xr-x   1 oracle   qmail       4381 Jul 16 13:20 .profile
-rwxr-xr-x   1 oracle   qmail       3648 Sep  1  2000 .profile_old
-rw-------   1 oracle   dba         2264 Sep  3 08:06 .sh_history
drwxr-xr-x   2 oracle   dba          512 May 10 11:10 .ssh
-rw-------   1 oracle   dba         3861 May 29 06:03 Mailbox
-rw-r--r--   1 oracle   dba        12632 Apr 11 16:09 ad.sql
drwxr-xr-x   2 oracle   dba          512 Jan 26  2001 adamf_techeops
drwxr-xr-x   5 oracle   dba          512 Sep  4  2000 admin
-rwxr-xr-x   1 oracle   dba           55 Aug 22 11:56 afiedt.buf

Below is a listing of each of the columns in the ls –al command so their meaning is understood.

Table 2.5:  The Columns in the ls –al UNIX Command

The first column in the ls –al command shows the file permissions.  The permissions are a set of letters arranged in a group of three, one for the file owner, one for the file group and another for the world (Figure 1-3).

The third and fourth columns of the ls –al command lists the owner and group of the file.   Note that if there is super-user authority (root), change the owner and group of any file with the chown command. The fifth column is the file size in bytes, the sixth column lists the last modified date and the last column is the name of the file.

Displaying “Dot” files in UNIX

The –a option of the ls command is used to display the “dot” files, which are not normally seen with the ls command.  “dot” files are those files whose name begins with a period (“.”).  Some “dot” files that are of special interest to the Oracle DBA:

Command history files – These file keep a complete audit of each and every UNIX command issued by the UNIX user. These include .sh_history, .bash_history and .ksh_history.

Login files – These files contain login scripts that are executed every time the user signs on to UNIX.  These include .profile, .cshrc, .kshrc and .bshrc,.

For more details on Oracle utilities, see the book "Advanced Oracle Utilities" by Bert Scalzo, Donald K. Burleson, and Steve Callan. You can buy it direct from the publisher for 30% off directly from Rampant TechPress.