Editing Solaris 10 System Administration Part I (section)

=== Identifying file types ===

Solaris has four main file types:

<table style="text-align: left; width: 50%;" border="1"
 cellpadding="2" cellspacing="0">
<tr>
     <td>regular or ordinary files</td>
     <td>store one or more types of data</td>
</tr>
<tr>
     <td>directories</td>
     <td>store one or more types of data</td>
</tr>
<tr>
     <td>symbolic links</td>
     <td>store one or more types of data</td>
</tr>
<tr>
     <td>device files</td>
     <td>does not store data</td>
</tr>
</table>

Use ls command with -l option to distinguish different file types

The first character of each line indicates file type

<insert image of ls -l output with dictionary>

<table style="text-align: left; width: 50%;" border="1"
 cellpadding="2" cellspacing="0">
<tr>
     <td>-</td>
     <td>regular files</td>
</tr>
<tr>
     <td>d</td>
     <td>directories</td>
</tr>
<tr>
     <td>l</td>
     <td>symbolic links</td>
</tr>
<tr>
     <td>b</td>
     <td>block-special device files</td>
</tr>
<tr>
     <td>c</td>
     <td>character-special device files</td>
</tr>
</table>

Examples on v240:
<pre>
# cd /etc
# ls -l
total 650
lrwxrwxrwx   1 root     root          14 May  3 15:34 TIMEZONE -> ./default/init
drwxr-xr-x   6 root     other        512 May  3 16:15 X11
drwxr-xr-x   2 adm      adm          512 May  3 16:19 acct
-rw-r--r--   1 root     sys          253 Aug  6  2010 aggregation.conf
lrwxrwxrwx   1 root     root          14 May  3 16:03 aliases -> ./mail/aliases
drwxr-xr-x   7 root     bin          512 May  3 16:11 apache
drwxr-xr-x   2 root     bin          512 May  3 15:54 apache2
*****output truncated*****
</pre>

<pre>
# pwd
/devices/pci@1c,600000/scsi@2
# ls -l
total 8
drwxr-xr-x   2 root     sys          512 May  3 16:25 sd@0,0
brw-r-----   1 root     sys       32,  0 Jul  7 13:54 sd@0,0:a
crw-r-----   1 root     sys       32,  0 Jul 14 16:50 sd@0,0:a,raw
</pre>

==== directories ====

directories only store information on file name to inode number relationships


A directory contains data for files that are logically located within directory

==== Regular files ====

Most common file types found in Solaris are regular files. Regular files can store different types of data including ASCII text or binary data.

==== Symbolic links ====

a symbolic link is a file that points to another file & contain only one type of data

a symbolic link contains the path name of the file to which it points & the file can be located on other file systems

the size of a symbolic link always matches the number of characters in the path name it contains

Example:

after the '->' there are 19 characters & the 19 before May is the file size.
<pre>
# ls -l /etc/prtvtoc
lrwxrwxrwx   1 root     root          19 May  3 15:34 prtvtoc -> ../usr/sbin/prtvtoc
</pre>

symbolic links can point to regular files, directories, other symbolic links, & device files.

symbolic links can be absolute or relative path names

===== ln command =====

ln command with -s option creates a symbolic link

<insert example of creating symbolic link>

<insert picture of relationship between link & file>

==== device files ====

device file provides access to a device

When using long listing on file the size field is populated by two numbers separated by comma

The two numbers are called major & minor device numbers

major device # identifies the specific device driver required to access device
minor device # identifies specific unit of the type that the device driver controls

Long listing:
<pre>bash-3.00$ ls -l | grep pci
drwxr-xr-x   4 root     sys          512 May  3 16:25 pci@1c,600000
crw-------   1 root     sys      109, 767 Jul 14 16:50 pci@1c,600000:devctl
crw-------   1 root     sys      109, 764 Jul 14 16:50 pci@1c,600000:intr
crw-------   1 root     sys      109, 765 Jul 14 16:50 pci@1c,600000:reg
drwxr-xr-x   5 root     sys          512 May  3 16:25 pci@1d,700000
crw-------   1 root     sys      109, 1023 Jul 14 16:50 pci@1d,700000:devctl
crw-------   1 root     sys      109, 1020 Jul 14 16:50 pci@1d,700000:intr
crw-------   1 root     sys      109, 1021 Jul 14 16:50 pci@1d,700000:reg
drwxr-xr-x   6 root     sys          512 May  3 16:25 pci@1e,600000
crw-------   1 root     sys      109, 511 Jul 14 16:50 pci@1e,600000:devctl
crw-------   1 root     sys      109, 508 Jul 14 16:50 pci@1e,600000:intr
crw-------   1 root     sys      109, 509 Jul 14 16:50 pci@1e,600000:reg
drwxr-xr-x   4 root     sys          512 May  3 16:25 pci@1f,700000
crw-------   1 root     sys      109, 255 Jul 14 16:50 pci@1f,700000:devctl
crw-------   1 root     sys      109, 252 Jul 14 16:50 pci@1f,700000:intr
crw-------   1 root     sys      109, 253 Jul 14 16:50 pci@1f,700000:reg</pre>

'''File pci@1c,600000:devctl refers to major device # 109 & minor device # 767'''

You can also use the <code>file</code> command:
<pre>bash-3.00$ file pci@1c,600000:devctl
pci@1c,600000:devctl:   character special (109/767)</pre>

Use <code>devfsadm</code> command to create new device files

A relationship exists between device file & device it controls. Major & minor device #s contained in inode establish relationship

<image showing relationship from above example>

Verify device driver is available as kernel module:
<pre>bash-3.00# modinfo -w | grep -w scsi
 22  1313a40  122a8   -   1  scsi (SCSI Bus Utility Routines)
bash-3.00# modinfo -c | grep -w scsi
 22          1 scsi                             LOADED/INSTALLED
bash-3.00# modinfo -w | grep -w iscsi            
 96 7b600000  328c8 279   1  iscsi (Sun iSCSI Initiator v20100714-0)
bash-3.00# modinfo -c | grep -w iscsi
 96          1 iscsi                            LOADED/INSTALLED</pre>

device files are categorized as character-special [character or raw devices] or block-special devices [block devices]

device files in each category interact with devices differently

===== character-special device files =====

File type of "c" is character-special device file & data is accessed as a data stream

<pre>crw-------   1 root     sys      109, 767 Jul 14 16:50 pci@1c,600000:devctl</pre>

Result of <code>file</code> command:
<pre>bash-3.00# file pci@1c,600000:devctl
pci@1c,600000:devctl:   character special (109/767)</pre>

===== block-special device files =====

File type of "b" is a block-special device file & for disk devices, block-special device files call for I/O operations based on a defined block size

Block size depends on particular device file

<example of long listing of block file>

data transferred between process & block-special device is first stored in kernel-managed memory-based cache

block devices allow random seeks to be performed [character devices do not]

==== hard links ====

hard link is association between file name & an inode

inode keeps count # of file names associated with it (hard links)

output of long listing will show '''link count''' or total # of hard links to a file

<pre>bash-3.00# ls -l mnttab
-r--r--r--   5 root     root        1539 Jul  7 13:55 mnttab
</pre>

/etc/mnttab file has 5 link counts or hard links [between file permissions & owner]

===== creating new hard links =====

<code>ln</code> command creates new hard links to regular files

<pre>$ ln file5 file6
$ ln file5 file7
$ ln file7 file8
$ ls -il
total 64868
        54 -rw-------   1 paul     labnet    555969 May  6 13:52 file.7z
        55 -rw-r--r--   1 paul     labnet        53 May  6 13:23 file1.gz
        39 -rw-r--r--   1 paul     labnet    739704 May  6 13:42 file2.gz
        41 -rw-r--r--   1 paul     labnet         0 May  5 12:35 file3
        50 -rw-r--r--   1 paul     labnet   3976616 May  6 13:37 file4
        52 -rw-r--r--   4 paul     labnet   3976541 May  6 13:43 file5
        52 -rw-r--r--   4 paul     labnet   3976541 May  6 13:43 file6
        52 -rw-r--r--   4 paul     labnet   3976541 May  6 13:43 file7
        52 -rw-r--r--   4 paul     labnet   3976541 May  6 13:43 file8
        53 -rw-r--r--   1 paul     labnet   11934208 May  6 13:48 filetar.tar
        42 drwxr-xr-x   2 paul     labnet       512 May  5 12:45 subdir1
$</pre>

The <code>ln</code> command created files 6-8. Now files 5-8 refer to same inode [52]. Notice link count is now 4 for each of the files. You must use -i option with <code>ls</code> command to view inodes

Use find command with -inum option to find files with same inode
<pre>$ find . -inum 52
./file6
./file7
./file5
./file8</pre>

<insert image showing file name to inode association>

===== deleting hard links =====

delete files normally & link count will decrease automatically

<pre>$ rm file8
$ ls -li
total 57076
        54 -rw-------   1 paul     labnet    555969 May  6 13:52 file.7z
        55 -rw-r--r--   1 paul     labnet        53 May  6 13:23 file1.gz
        39 -rw-r--r--   1 paul     labnet    739704 May  6 13:42 file2.gz
        41 -rw-r--r--   1 paul     labnet         0 May  5 12:35 file3
        50 -rw-r--r--   1 paul     labnet   3976616 May  6 13:37 file4
        52 -rw-r--r--   3 paul     labnet   3976541 May  6 13:43 file5
        52 -rw-r--r--   3 paul     labnet   3976541 May  6 13:43 file6
        52 -rw-r--r--   3 paul     labnet   3976541 May  6 13:43 file7
        53 -rw-r--r--   1 paul     labnet   11934208 May  6 13:48 filetar.tar
        42 drwxr-xr-x   2 paul     labnet       512 May  5 12:45 subdir1
$</pre>

Once all files with same inode are deleted the inode will be deleted

==== Examples ====

Find files that match inode on same file system

<pre># ls -l /etc/init.d/apache
-rwxr--r--   6 root     sys         2452 Jun 23  2010 /etc/init.d/apache</pre>

/etc/init.d/apache file has a 6 link count

<pre># ls -i /etc/init.d/apache
      2955 /etc/init.d/apache</pre>

/etc/init.d/apache inode is 2955

<pre># find /etc -inum 2955 -exec ls -i {} \;
      2955 /etc/init.d/apache
      2955 /etc/rc0.d/K16apache
      2955 /etc/rc1.d/K16apache
      2955 /etc/rc2.d/K16apache
      2955 /etc/rc3.d/S50apache
      2955 /etc/rcS.d/K16apache</pre>

The <code>find</code> command with -inum option allows you to search by inode. Now I know which files are pointing to same location as /etc/init.d/apache