I have recently migrated from Windows to Ubuntu.

My current locale shows below output :-

    cha@COMPUTER:~$ locale
    LANG=en_IN
    LANGUAGE=en_IN:en
    LC_CTYPE="en_IN"
    LC_NUMERIC="en_IN"
    LC_TIME="en_IN"
    LC_COLLATE="en_IN"
    LC_MONETARY="en_IN"
    LC_MESSAGES="en_IN"
    LC_PAPER="en_IN"
    LC_NAME="en_IN"
    LC_ADDRESS="en_IN"
    LC_TELEPHONE="en_IN"
    LC_MEASUREMENT="en_IN"
    LC_IDENTIFICATION="en_IN"
    LC_ALL=

When I am trying to install CHMSee (or any other Application) using UBUNTU Software Center. I am getting below error.

    installArchives() failed: perl: warning: Setting locale failed.
    perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "en_IN.ISO8859-1"
        are supported and installed on your system.
    perl: warning: Falling back to the standard locale ("C").
    locale: Cannot set LC_CTYPE to default locale: No such file or directory
    locale: Cannot set LC_MESSAGES to default locale: No such file or directory
    locale: Cannot set LC_ALL to default locale: No such file or directory
    perl: warning: Setting locale failed.
    perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "en_IN.ISO8859-1"
        are supported and installed on your system.
    perl: warning: Falling back to the standard locale ("C").
    locale: Cannot set LC_CTYPE to default locale: No such file or directory
    locale: Cannot set LC_MESSAGES to default locale: No such file or directory
    locale: Cannot set LC_ALL to default locale: No such file or directory
    perl: warning: Setting locale failed.
    perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "en_IN.ISO8859-1"
        are supported and installed on your system.
    perl: warning: Falling back to the standard locale ("C").
    locale: Cannot set LC_CTYPE to default locale: No such file or directory
    locale: Cannot set LC_MESSAGES to default locale: No such file or directory
    locale: Cannot set LC_ALL to default locale: No such file or directory
    perl: warning: Setting locale failed.
    perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LANG = "en_IN.ISO8859-1"
        are supported and installed on your system.
    perl: warning: Falling back to the standard locale ("C").
    locale: Cannot set LC_CTYPE to default locale: No such file or directory
    locale: Cannot set LC_MESSAGES to default locale: No such file or directory
    locale: Cannot set LC_ALL to default locale: No such file or directory
    Selecting previously unselected package libchm1.
    (Reading database ... 
    (Reading database ... 5%
    (Reading database ... 10%
    (Reading database ... 15%
    (Reading database ... 20%
    (Reading database ... 25%
    (Reading database ... 30%
    (Reading database ... 35%
    (Reading database ... 40%
    (Reading database ... 45%
    (Reading database ... 50%
    (Reading database ... 55%
    (Reading database ... 60%
    (Reading database ... 65%
    (Reading database ... 70%
    (Reading database ... 75%
    (Reading database ... 80%
    (Reading database ... 85%
    (Reading database ... 90%
    (Reading database ... 95%
    (Reading database ... 100%
    (Reading database ... 207053 files and directories currently installed.)
    Unpacking libchm1 (from .../libchm1_2%3a0.40a-1_i386.deb) ...
    Selecting previously unselected package libjavascriptcoregtk-1.0-0.
    Unpacking libjavascriptcoregtk-1.0-0 (from .../libjavascriptcoregtk-1.0-0_1.8.0-0ubuntu2_i386.deb) ...
    Selecting previously unselected package libwebkitgtk-1.0-common.
    Unpacking libwebkitgtk-1.0-common (from .../libwebkitgtk-1.0-common_1.8.0-0ubuntu2_all.deb) ...
    Selecting previously unselected package libwebkitgtk-1.0-0.
    Unpacking libwebkitgtk-1.0-0 (from .../libwebkitgtk-1.0-0_1.8.0-0ubuntu2_i386.deb) ...
    Selecting previously unselected package chmsee.
    Unpacking chmsee (from .../chmsee_1.3.0-2ubuntu2_i386.deb) ...
    Processing triggers for bamfdaemon ...
    Rebuilding /usr/share/applications/bamf.index...
    Processing triggers for desktop-file-utils ...
    Processing triggers for gnome-menus ...
    Processing triggers for hicolor-icon-theme ...
    Processing triggers for man-db ...
    locale: Cannot set LC_CTYPE to default locale: No such file or directory
    locale: Cannot set LC_MESSAGES to default locale: No such file or directory
    locale: Cannot set LC_ALL to default locale: No such file or directory
    Setting up qmail (1.06-4) ...

    The hostname -f command returned: $1

    Your system needs to have a fully qualified domain name (fqdn) in
    order to install the var-qmail packages.

    Installation aborted.

    dpkg: error processing qmail (--configure):
     subprocess installed post-installation script returned error exit status 1
    dpkg: dependency problems prevent configuration of qmail-run:
     qmail-run depends on qmail (>= 1.06-2.1); however:
      Package qmail is not configured yet.
    dpkg: error processing qmail-run (--configure):
     dependency problems - leaving unconfigured
    Setting up libchm1 (2:0.40a-1) ...
    No apport report written because the error message indicates its a followup error from a previous failure.
    Setting up libjavascriptcoregtk-1.0-0 (1.8.0-0ubuntu2) ...
    Setting up libwebkitgtk-1.0-common (1.8.0-0ubuntu2) ...
    Setting up libwebkitgtk-1.0-0 (1.8.0-0ubuntu2) ...
    Setting up chmsee (1.3.0-2ubuntu2) ...
    Processing triggers for libc-bin ...
    ldconfig deferred processing now taking place
    Errors were encountered while processing:
     qmail
     qmail-run
    Error in function: 
    SystemError: E:Sub-process /usr/bin/dpkg returned an error code (1)
    Setting up qmail (1.06-4) ...

    The hostname -f command returned: $1

    Your system needs to have a fully qualified domain name (fqdn) in
    order to install the var-qmail packages.

    Installation aborted.

    dpkg: error processing qmail (--configure):
     subprocess installed post-installation script returned error exit status 1
    dpkg: dependency problems prevent configuration of qmail-run:
     qmail-run depends on qmail (>= 1.06-2.1); however:
      Package qmail is not configured yet.
    dpkg: error processing qmail-run (--configure):
     dependency problems - leaving unconfigured

Can someone please help me in resolving this issue. The elaboration would be most appreciated since I am very new to this.

Thanks,

Anshuman Chakraborty