The /etc/release file was first introduced on Solaris 2.5.1 Hardware 4/97 and can be found on all subsequent Solaris versions.
The purpose of the /etc/release file is to easily determine the base OS or upgraded OS installed.
The /etc/release file is the same whether obtained from the installed operating system, the cdrom, or the installation image on hard disk.
EXAMPLE:
/etc/release
/cdrom/solaris_2_5_1_hw1197_sparc/s0/Solaris_2.5.1/SUNWsolnm/reloc/etc
image_path.../Solaris_2.5.1/SUNWsolnm/reloc/etc
Below are a listing of the contents for the specified OS versions.
=========================================================================
SOLARIS 2.5.1
=========================================================================
Solaris 2.5.1 4/97
image_path/Solaris_2.5.1/SUNWsolnm/reloc/etc
# more release
Solaris 2.5.1 Hardware: 4/97 SPARC
Copyright 1997 Sun Microsystems, Inc. All Rights Reserved.
Manufactured in the USA 16 April 1997
-----------------------------------------------------------------------
Solaris 2.5.1 8/97
/image_path/Solaris_2.5.1/SUNWsolnm/reloc/etc
# more release
Solaris 2.5.1 Hardware: 8/97 s596hw2_09 SPARC
Copyright 1997 Sun Microsystems, Inc. All Rights Reserved.
Manufactured in the USA 29 July 1997
-----------------------------------------------------------------------
Solaris 2.5.1 11/97
/image_path/Solaris_2.5.1/SUNWsolnm/reloc/etc
# more release
Solaris 2.5.1 Hardware 11/97 s596hw3_11 SPARC
Copyright 1997 Sun Microsystems, Inc. All Rights Reserved.
Manufactured in the USA 04 November 1997
=========================================================================
SOLARIS 2.6
=========================================================================
Solaris 2.6
/cdrom/sol_2_6_sparc_smcc_svr/s0/Solaris_2.6/Product/SUNWsolnm/reloc/etc
# more release
Solaris 2.6 s297s_smccServer_37cshwp SPARC
Copyright 1996 Sun Microsystems, Inc. All Rights Reserved.
Manufactured in the USA 18 July 1997
-----------------------------------------------------------------------
Solaris 2.6 3/98
# more release
Solaris 2.6 HW:2 s297s_hw2smccDesktop_09 SPARC
Copyright 1998 Sun Microsystems, Inc. All Rights Reserved.
Assembled on 03 February 1998
-----------------------------------------------------------------------
Solaris 2.6 5/98
# more release
Solaris 2.6 5/98 s297s_hw3smccDesktop_09 SPARC
Copyright 1998 Sun Microsystems, Inc. All Rights Reserved.
Assembled on 24 April 1998
-----------------------------------------------------------------------
Solaris 2.6 Maintenance Update 2
# more /etc/release
Solaris 2.6 s297s_smccServer_37cshwp SPARC
Copyright 1996 Sun Microsystems, Inc. All Rights Reserved.
Manufactured in the USA 18 July 1997
Solaris 2.6 Maintenance Update 2, Assembled April 1998
=========================================================================
SOLARIS 7
=========================================================================
Solaris 7 FCS
/cdrom/sol_7_sparc_sun_srvr/s0/Solaris_2.7/Product/SUNWsolnm/reloc/etc
# more release
Solaris 7 s998s_SunServer_21al2b SPARC
Copyright 1998 Sun Microsystems, Inc. All Rights Reserved.
Assembled 06 October 1998
-----------------------------------------------------------------------
Solaris 7 3/99
/cdrom/sol_7_399_sparc_sun_srvr/s0/Solaris_2.7/Product/SUNWsolnm/reloc/etc
# more release
Solaris 7 3/99 s998s_u1SunServer_10 SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 26 January 1999
-----------------------------------------------------------------------
Solaris 7 5/99
/cdrom/sol_7_599_sparc_sun_srvr/s0/Solaris_2.7/Product/SUNWsolnm/reloc/etc
# more release
Solaris 7 5/99 s998s_u2SunServer_09 SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 19 April 1999
-----------------------------------------------------------------------
Solaris 7 8/99
/cdrom/sol_7_899_sparc_sun_srvr/s0/Solaris_2.7/Product/SUNWsolnm/reloc/etc
# more release
Solaris 7 8/99 s998s_u3SunServer_11 SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 30 July 1999
-----------------------------------------------------------------------
Solaris 7 11/99
/cdrom/sol_7_1199_sparc_sun_srvr/s0/Solaris_2.7/Product/SUNWsolnm/reloc/etc
# more release
Solaris 7 11/99 s998s_u4SunServer_10 SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 15 October 1999
=========================================================================
SOLARIS 8
=========================================================================
Solaris 8 Beta
/cdrom/sol_8_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 s28_27b SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 24 July 1999
-----------------------------------------------------------------------
Solaris 8 Beta Refresh
/cdrom/sol_8_sparc#1/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 s28_32d SPARC
Copyright 1999 Sun Microsystems, Inc. All Rights Reserved.
Assembled 08 October 1999
-----------------------------------------------------------------------
Solaris 8 FCS
/cdrom/sol_8_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 s28_38shwp2 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 21 January 2000
-----------------------------------------------------------------------
Solaris 8 Update 1 (6/00)
/cdrom/sol_8_600_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc/release
Solaris 8 6/00 s28s_u1wos_08 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 26 April 2000
-----------------------------------------------------------------------
Solaris 8 Maintenance Update 1 (MU1)
# more /etc/release
Solaris 8 s28_38shwp2 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 21 January 2000
Solaris 8 Maintenance Update 1 applied
-----------------------------------------------------------------------
Solaris 8 Update 2 (10/00)
/cdrom/sol_8_1000_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc/release
Solaris 8 10/00 s28s_u2wos_11b SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 31 August 2000
-----------------------------------------------------------------------
Solaris 8 Maintenance Update 2 (MU2)
# more /etc/release
Solaris 8 s28_38shwp2 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 21 January 2000
Solaris 8 Maintenance Update 2 applied
-----------------------------------------------------------------------
Solaris 8 Update 3 (1/01)
/cdrom/sol_8_u3_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 1/01 s28s_u3wos_08 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 28 November 2000
-----------------------------------------------------------------------
Solaris 8 Update 4 (4/01) Beta
/cdrom/sol_8_401_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 4/01 s28s_u4wos_03 SPARC
Copyright 2000 Sun Microsystems, Inc. All Rights Reserved.
Assembled 11 December 2000
-----------------------------------------------------------------------
Solaris 8 Update 4 (4/01)
/cdrom/sol_8_401_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 4/01 s28s_u4wos_08 SPARC
Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
Assembled 01 March 2001
-----------------------------------------------------------------------
Solaris 8 Update 5 (7/01)
/cdrom/sol_8_701_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 7/01 s28s_u5wos_08 SPARC
Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
Assembled 06 June 2001
-----------------------------------------------------------------------
Solaris 8 Update 6 (10/01) Beta
/cdrom/sol_8_1001_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 10/01 s28s_u6wos_03 SPARC
Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
Assembled 18 June 2001
-----------------------------------------------------------------------
Solaris 8 Update 6 (10/01)
/cdrom/sol_8_1001_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 10/01 s28s_u6wos_08a SPARC
Copyright 2001 Sun Microsystems, Inc. All Rights Reserved.
Assembled 12 September 2001
-----------------------------------------------------------------------
Solaris 8 Update 7 (2/02)
/cdrom/sol_8_202_sparc/s0/Solaris_8/Product/SUNWsolnm/reloc/etc
# more release
Solaris 8 2/02 s28s_u7wos_08a SPARC
Copyright 2002 Sun Microsystems, Inc. All Rights Reserved.
Assembled 18 December 2001
=========================================================================
SOLARIS 9
=========================================================================
Solaris 9 Beta
/cdrom/sol_9_sparc/s0/Solaris_9/Product/SUNWsolnm/reloc/etc
# more release
Solaris 9 s9_41e SPARC
Copyright 2001 Sun Microsystems, Inc. All Right