The CHECKSUM command invokes a utility to calculate one or
more checksums for OpenVMS files. The result, or checksum, is
available in the DCL symbol CHECKSUM$CHECKSUM.
For a detailed description of the CHECKSUM utility, see the
CHECKSUM command description in the VSI OpenVMS DCL Dictionary.
Format
CHECKSUM filespec
1 – Parameter
filespec
Specifies the name of an existing file to be checksummed. The
asterisk (*) and percent sign (%) wildcard characters are
allowed in the file specification.
2 – Qualifiers
2.1 /ALGORITHM
/ALGORITHM=option
/ALGORITHM=XOR (default)
Selects the algorithm used for file checksums. The default is the
XOR algorithm for data within records, as used by the previous
Checksum utilities on OpenVMS Alpha systems. Options include:
o CRC - A CRC-32 algorithm for all bytes within the file
(possible record structures are ignored); this algorithm is
also known as AUTODIN II, Ethernet, or FDDI CRC.
o MD5 - The MD5 digest, as published by Ronald L. Rivest
(RFC 1321), for all bytes within the file (possible record
structures are ignored).
o XOR - An XOR algorithm for all data, according to the record
structure of the file.
2.2 /ALPHA
Calculates an Alpha-type checksum and is only useful with the
/IMAGE qualifier on Integrity server systems (that is, it
checksums Alpha images on Integrity server systems). It is set
by default on Alpha platforms.
2.3 /FILE
/FILE (default)
Calculates a file checksum.
By default, the XOR algorithm (/ALGORITHM=XOR) is used for the
checksum. The /FILE qualifier also implies a default file type
of .DAT. By default, unsigned decimal checksum value is saved in
the DCL symbol CHECKSUM$CHECKSUM and not output to the screen. By
specifying /SHOW=DATA, the full filename of the specified input
file is output in addition to the file checksum, an unsigned
decimal value.
The /ALPHA, /I64, or /VAX platform qualifiers do not influence
the file checksum result. However, /ALPHA and /VAX prohibit the
/SHOW qualifier because these qualifiers were not available on
the original Checksum utility for Alpha systems.
2.4 /I64
Calculates an I64-type checksum and is only useful on Alpha
systems with /IMAGE or /OBJECT (that is, it checksums Integrity
servers images or objects on Alpha systems). The /I64 qualifier
is set by default on Integrity servers platforms.
2.5 /IMAGE
Calculates a checksum of all image bytes. The image structure
is followed to include only the image bytes into the checksum.
Invariant data, such as the linker version and the link date, are
omitted.
For Integrity servers images (that is, Integrity servers
formatted files), a CRC checksum is calculated and additional
information is output to SYS$OUTPUT, including the following:
o The resulting full filename and checksums for the image
segments
o The header checksums and the overall image checksum
The output values are shown in hexadecimal notation. The DCL
symbol, CHECKSUM$CHECKSUM, shows the result in hexadecimal
notation.
For Alpha and VAX images, an XOR checksum is calculated and
additional information is output to SYS$OUTPUT:
o The resulting full filename and checksums for the image
sections
o The header checksum and the overall image checksum
The output checksum values are in hexadecimal notation. However,
the result in the DCL symbol CHECKSUM$CHECKSUM is in unsigned
decimal notation.
NOTE
For Alpha and VAX images, the unsigned decimal notation
of the checksum value in the DCL symbol CHECKSUM$CHECKSUM
retains compatibility with the previous checksum tool.
The /IMAGE qualifier implies the default file type of .EXE. For
Integrity servers images, this qualifier also implies the default
keyword values HEADERS and SEGMENTS for the /SHOW qualifier.
2.6 /OBJECT
Calculates a CRC checksum of all Integrity servers object bytes.
The /OBJECT qualifier follows the ELF-64 object structure to
include only the object bytes into the checksum. Invariant data,
as the language processor version and the generation date, are
omitted.
Additional information is output to SYS$OUTPUT, including the
following:
o The resulting full filename of the specified input file
o The checksums for the object sections, headers, and the
overall object checksum
The output checksum values are in hexadecimal notation. The
result provided in the DCL symbol, CHECKSUM$CHECKSUM, is in
hexadecimal notation.
The /OBJECT qualifier implies the default file type of .OBJ. This
qualifier also implies the default keyword values HEADERS and
SECTIONS for the /SHOW qualifier.
On Alpha platforms, it is only applicable with the /Integrity
servers qualifier.
2.7 /OUTPUT
/OUTPUT[=filespec]
/NOOUTPUT
The /OUTPUT qualifier controls where the output of the command is
sent. The /NOOUTPUT qualifier suppresses output.
If you specify /OUTPUT and a file specification
(/OUTPUT=filespec), the output is sent to the specified file,
rather than to the current output device, SYS$OUTPUT. If you do
not enter the qualifier, or if you enter the /OUTPUT qualifier
without a file specification, the output is sent to SYS$OUTPUT.
Using the /OUTPUT qualifier does not affect the result (that is,
the DCL symbol CHECKSUM$CHECKSUM).
2.8 /SHOW
/SHOW=(option[,...])
Controls which checksum and additional information is output to
the device.
Options for this qualifier are as follows:
o ALL - Sets all of the applicable options, with the following
restrictions:
- For file checksums, only the DATA keyword is allowed.
- For image checksums, all keywords are allowed.
- For object checksums, the SEGMENT keyword is not allowed.
o DATA - Outputs the full file name and the file checksum. For
compatibility, this option is available for /FILE.
o EXCLUDED - Formats the data excluded from the image or object
checksums.
o HEADERS - Output checksums of all Integrity servers headers.
This option is set by default for /IMAGE and /OBJECT.
o SECTIONS - Output checksums of all ELF-64 sections. This
option is set by default for /OBJECT.
o SEGMENTS - Output checksums of all ELF-64 program segments.
This option is set by default for /IMAGE.
2.9 /VAX
Calculates a VAX-type checksum and is only useful on Integrity
servers or Alpha systems with /IMAGE to checksum VAX images on
non-VAX systems.
3 – Examples
The CHECKSUM/IMAGE command results in different output for
Integrity servers and Alpha platforms. Because there are
different image structures, the names for the checksums differ:
o The checksum for Alpha outputs the section number as BLISS
constant: %D'1' whereas the Integrity servers checksum
outputs decimal numbers.
o The checksum for Alpha outputs the checksums as BLISS
constant: %X'6C5404CB' whereas the Integrity servers
checksum outputs DCL-style hexadecimal numbers.
o The DCL symbol on Alpha is an unsigned decimal value,
whereas the DCL symbol for Integrity servers is a
hexadecimal value.
On Alpha systems:
$ CHECKSUM/IMAGE HELLO.EXE
file DISK$USER:[JOE]HELLO.EXE;10
image section %D'1' checksum is %X'6C5404CB'
image section %D'2' checksum is %X'E29D6A3A'
image section %D'3' checksum is %X'114B0786'
image header checksum is %X'00000204'
checksum of all image sections is %X'9F826977'
$ SHOW SYMBOL CHECKSUM$CHECKSUM
CHECKSUM$CHECKSUM = "2676124023"
On Integrity server systems:
$ CHECKSUM/IMAGE FOOBAR.EXE
File DISK$USER:[JOE]FOOBAR.EXE;3
Checksum program segment 0: %X18E293D7
Checksum program segment 1: %XEFBCE000
Checksum program segment 2: %XA6D02DD5
Checksum program segment 3: %X30130E3E
Checksum dynamic segment %X0F704080
Elf header checksum: %X7A6AC80F
Elf program header checksum: %XBF6B41D8
Elf section header checksum: %X6C770CF6
Elf (object/image) checksum: %X2EEE7726
$ SHOW SYMBOL CHECKSUM$CHECKSUM
CHECKSUM$CHECKSUM = "2EEE7726"