HOST variables comes from the web server, so it doesn't exist with CLI.
There is also HOSTNAME environment variable, which is usually set on *nix systems.

Thanks John..

But I got the $_SERVER variable values in CLI itself.

Array structure got from the CLI :
-------------------------------------------------

["_SERVER"]=>
  array(39) {
    ["USER"]=>
    string(7) "mytoday"
    ["LOGNAME"]=>
    string(7) "mytoday"
    ["HOME"]=>
    string(51) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com"
    ["PATH"]=>
    string(244) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/bin:/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/checkmail:/usr/bin:/usr/sbin:/usr/local/bin:/bin:/usr/bin:/usr/ucb:usr/etc:/usr/etc:/usr/local/mysql/bin:/disk2/download/tidy-1.2/tidy:."
    ["MAIL"]=>
    string(23) "/var/spool/mail/mytoday"
    ["SHELL"]=>
    string(9) "/bin/tcsh"
    ["SSH_CLIENT"]=>
    string(28) "::ffff:192.168.2.104 3743 22"
    ["SSH_CONNECTION"]=>
    string(48) "::ffff:192.168.2.104 3743 ::ffff:192.168.1.18 22"
    ["SSH_TTY"]=>
    string(11) "/dev/pts/10"
    ["TERM"]=>
    string(5) "vt100"
    ["HOSTTYPE"]=>
    string(10) "i386-linux"
    ["VENDOR"]=>
    string(5) "intel"
    ["OSTYPE"]=>
    string(5) "linux"
    ["MACHTYPE"]=>
    string(4) "i386"
    ["SHLVL"]=>
    string(1) "1"
    ["PWD"]=>
    string(72) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium"
    ["GROUP"]=>
    string(7) "mytoday"
    ["HOST"]=>
    string(17) "php5.greynium.com"
    ["REMOTEHOST"]=>
    string(13) "192.168.2.104"
    ["LS_COLORS"]=>
    string(440) "no=00:fi=00:di=01;34:ln=01;36:pi=40;33:so=01;35:bd=40;33;01:cd=40;33;01:or=01;05;37;41:mi=01;05;37;41:ex=01;32:*.cmd=01;32:*.exe=01;32:*.com=01;32:*.btm=01;32:*.bat=01;32:*.sh=01;32:*.csh=01;32:*.tar=01;31:*.tgz=01;31:*.arj=01;31:*.taz=01;31:*.lzh=01;31:*.zip=01;31:*.z=01;31:*.Z=01;31:*.gz=01;31:*.bz2=01;31:*.bz=01;31:*.tz=01;31:*.rpm=01;31:*.cpio=01;31:*.jpg=01;35:*.gif=01;35:*.bmp=01;35:*.xbm=01;35:*.xpm=01;35:*.png=01;35:*.tif=01;35:"
    ["G_BROKEN_FILENAMES"]=>
    string(1) "1"
    ["SSH_ASKPASS"]=>
    string(38) "/usr/libexec/openssh/gnome-ssh-askpass"
    ["KDEDIR"]=>
    string(4) "/usr"
    ["LANG"]=>
    string(1) "C"
    ["SUPPORTED"]=>
    string(20) "en_US.UTF-8:en_US:en"
    ["LESSOPEN"]=>
    string(24) "|/usr/bin/lesspipe.sh %s"
    ["QTDIR"]=>
    string(15) "/usr/lib/qt-3.3"
    ["HOSTNAME"]=>
    string(17) "php5.greynium.com"
    ["INPUTRC"]=>
    string(12) "/etc/inputrc"
    ["CVSROOT"]=>
    string(55) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/CVS"
    ["errorlog"]=>
    string(51) "/disk2/v/apache/logs/mytoday.greynium.com-error.log"
    ["PHP_SELF"]=>
    string(12) "hosttest.php"
    ["SCRIPT_NAME"]=>
    string(12) "hosttest.php"
    ["SCRIPT_FILENAME"]=>
    string(12) "hosttest.php"
    ["PATH_TRANSLATED"]=>
    string(12) "hosttest.php"
    ["DOCUMENT_ROOT"]=>
    string(0) ""
    ["REQUEST_TIME"]=>
    int(1154779834)
    ["argv"]=>
    array(1) {
      [0]=>
      string(12) "hosttest.php"
    }
    ["argc"]=>
    int(1)
  }


Array structure from same php file when it is run as cronjob:
-----------------------------------------------------

  ["_SERVER"]=>
  array(16) {
    ["SHELL"]=>
    string(7) "/bin/sh"
    ["USER"]=>
    string(7) "mytoday"
    ["PATH"]=>
    string(13) "/usr/bin:/bin"
    ["PWD"]=>
    string(51) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com"
    ["SHLVL"]=>
    string(1) "1"
    ["HOME"]=>
    string(51) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com"
    ["LOGNAME"]=>
    string(7) "mytoday"
    ["_"]=>
    string(12) "/usr/bin/php"
    ["PHP_SELF"]=>
    string(85) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium/hosttest.php"
    ["SCRIPT_NAME"]=>
    string(85) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium/hosttest.php"
    ["SCRIPT_FILENAME"]=>
    string(85) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium/hosttest.php"
    ["PATH_TRANSLATED"]=>
    string(85) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium/hosttest.php"
    ["DOCUMENT_ROOT"]=>
    string(0) ""
    ["REQUEST_TIME"]=>
    int(1154779741)
    ["argv"]=>
    array(1) {
      [0]=>
      string(85) "/disk2/v/apache/htdocs/VIRTUAL/mytoday.greynium.com/public_html/greynium/hosttest.php"
    }
    ["argc"]=>
    int(1)
  }

So can you check the above two array structures and give me some ideas to get the hostname?

Moreover i checked the Environment variable also, hostname is not available there.

----
Mani