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File locking, grep and process killing on OpenVMS
Published: 06-05-2018 | Author: Remy van Elst | Text only version of this article
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Table of Contents
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On the DECUS OpenVMS system there is no curl or wget installed. I
wanted to download a remote C file to play around with the compiler and some
simple Hello World code, to get a feel of the build system. After a bit of
searching around the internet I was not able to find a command like curl or wget
to download a remote file. But, the searches led me to the OpenVMS port of curl,
which, I hoped, might be able to run on the DECUS system. Just like on a linux
system, running the binary under my user account, not install it system wide.
This ended up to be another adventure in which I figured out how to trace a
locked file to a process, grep the output of a process on OpenVMS and kill a
process. I did not get curl to work or compile my code, yet.
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The cc command is installed on the DECUS system:
$ CC /VERSION
HP C V7.3-010 on OpenVMS Alpha V8.4-2L2
When I get to my C code I will probably play around and write another small article on it here.
I downloaded the OpenVMS curl version from the vmsports project to my
computer. This is a project that compiles some software for OpenVMS, like
find, python and the one I was looking for, curl.
Using an sFTP client (filezilla), I uploaded the file to the DECUS system.
You're all probably thinking, why did he not just upload his C code with sFTP?
It simply did not occur, yet. When I was typing this article I thought, hmm. But
it was too late already, plus, I did learn new stuff in the process. As Bob Ross
would say, We don't make mistakes, just happy little accidents.
Filezilla however did complain and kept uploading the file. I closed Filezilla and went to check what was wrong via SSH. The file was there, leaving 5 versions. Probably an upload failure. Delete the files and try again.
-RMS-E-FLK, file currently locked by another user
I found out how to remove files and folders and wrote an article on that. To remove all versions of a file, using big scary wildcards:
$ DELETE vmsports*.*;*
%DELETE-W-FILNOTDEL, error deleting DSA3:[DECUSERVE_USER.EXAMPLE]VMSPORTS-AXPVMS-83-CURL-V0747--1.ZIP;1
-RMS-E-FLK, file currently locked by another user
Huh? I was not aware of multiple users or sessions in this account.
That error message refers to the RMS. I saw that here as well, I might
need to look into it some more.
I remembered something about locking when reading HELP pages earlier. In this
case, I tried the following:
$ SET FILE /UNLOCK VMSPORTS*.*;*
%SET-I-NOTLOCKED, DSA3:[DECUSERVE_USER.EXAMPLE]VMSPORTS-AXPVMS-83-CURL-V0747--1.ZIP;1 notlocked
That didn't help. Lets read the HELP:
$ HELP SET FILE /UNLOCK
SET
FILE
/UNLOCK
Clears a file marked as deaccess locked. Deaccess locking is
required by and used by those few applications that maintain
their own locking and consistency, typically without the use
of the OpenVMS distributed lock manager, and potentially also
without the use of RMS. When an application using deaccess
locking does not correctly deaccess the file (often due to an
application or system failure), the file is marked as locked, and
is thus inaccessible until the integrity of the contents of the
file are verified and the SET FILE/UNLOCK command is used.
This command does not affect the state of files that are locked
using RMS or the distributed lock manager.
For details on file deaccess locking, see the VSI OpenVMS I/O
User's Reference Manual, the ACP-QIO interface documentation, and
specifically the FIB$V_DLOCK option available on the IO$_CREATE
and IO$_ACCESS functions.
The SET FILE/UNLOCK command can clear the cause of the following
error message:
%SYSTEM-W-FILELOCKED, file is deaccess locked
However, this command cannot resolve the cause of the error
message:
%RMS-W-FLK, file currently locked by another user
That explains why it did not work. I suspected that there might be a process which locked my file.
Tracing a process' open files (lsof)
The HPe forums where of help here. First I needed the root disk name, which is
in the DIR output:
$ DIR
Directory DSA3:[DECUSERVE_USER.EXAMPLE]
$MAIN.TPU$JOURNAL;1 .VIMINFO;1 A.;1 FTP_SERVER.LOG;3
FTP_SERVER.LOG;1 LOGIN.COM;2 LOGIN.COM;1 LOGIN_COM.TPU$JOURNAL;1
MAIL.DIR;1 NOTES$NOTEBOOK.NOTE;1 SSH.DIR;1
SSH2.DIR;1 THREE.DIR;1 VMSPORTS-AXPVMS-83-CURL-V0747--1.ZIP;1
WWW.DIR;1
Using the SHOW DEV command we can list all processes that have files open:
$ SHOW DEV /FILES DSA3:
Files accessed on device DSA3: on 6-MAY-2018 10:31:44.88
Process name PID File name
00000000 insufficient privilege or object protection violation
00000000 insufficient privilege or object protection violation
Rob Brooks 0000043B insufficient privilege or object protection violation
HENKLE 0000F62B insufficient privilege or object protection violation
HENKLE 0000F62B insufficient privilege or object protection violation
HENKLE 0000F62B insufficient privilege or object protection violation
HENKLE 0000F62B insufficient privilege or object protection violation
[...]
HtHTNOTES_AN165 0000E541 insufficient privilege or object protection violation
<FTP_EXAMPLE> 00011591 [DECUSERVE_USER.EXAMPLE]FTP_SERVER.LOG;3
<FTP_EXAMPLE> 00011591 [DECUSERVE_USER.EXAMPLE]VMSPORTS-AXPVMS-83-CURL-V0747--1.ZIP;1
Except for the huge list of errors, it confirms that the FTP server has locked my file. One of the ways to release that lock is to stop the process. Another way is to reboot the system. The latter being a harsh solution if all else fails.
Search the output of one command for a string (pipe and grep) on OpenVMS
A big list of open files is not really usefull, and I don't want to see all those other users, none of my business. I wanted to filter that list to only show my user. Let's see if I can use a pipe and grep:
$ SHOW DEV /FILES DSA3: | GREP EXAMPLE
%DCL-W-MAXPARM, too many parameters - reenter command with fewer parameters
\|\
Nope, but I do suspect OpenVMS having an excellent solution for this problem. The DCL shell is over 30 years old so someone had to have this problem.
Browsing around the documentation I found this. It seems that if you want
to pipe output of a command, you first need to preface the command with the word
PIPE, then the command, then the | (pipe char), then another process.
There is no grep on OpenVMS unless you install it. There however is SEARCH.
A logical name, just like most of OpenVMS' workings.
The search command requires a filename. You can't just pipe output into it
directly, you need to tell it that it has to search the output. OpenVMS has the
SYS$OUTPUT and SYS$INPUT files for that when using the PIPE command.
Reading through the documentation:
|: Key pipe separator. The pipe connects theSYS$OUTPUTof one pipeline-segment command to theSYS$INPUTof the next command.
A few tries later I conjured up this command sequence:
$ PIPE SHOW DEV /FILES DSA3: | SEARCH SYS$INPUT EXAMPLE
Files accessed on device DSA3: on 6-MAY-2018 12:48:11.51
Process name PID File name
[...]
<FTP_EXAMPLE> 000111AF [DECUSERVE_USER.EXAMPLE]FTP_SERVER.LOG;4
To show all running processes including their PID's, use the SHOW SYSTEM
command. Combine that with out PIPE&SEARCH shell trick to get all the
processes of the current user. Searching the docs didn't gave me another
way or flag to the SHOW SYSTEM or SHOW PROCESS command to filter out one
specific user.
$ PIPE SHOW SYSTEM | SEARCH SYS$INPUT EXAMPLE
OpenVMS V8.4-2L2 on node EISNER 6-MAY-2018 12:49:45.02 Uptime 23 18:27:17
Pid Process Name State Pri I/O CPU Page flts Pages
[...]
0001156B EXAMPLE LEF 9 374 0 00:00:00.15 641 89
000111AF <FTP_EXAMPLE> LEF 5 46299 0 00:00:06.01 705 346 N
000115B0 EXAMPLE_62273 LEF 6 129 0 00:00:00.01 84 105 S
000115BE EXAMPLE_27501 CUR 0 4 188 0 00:00:00.04 138 165 S
000115BF EXAMPLE_29010 COM 4 185 0 00:00:00.02 128 152 S
It seems that we can try to stop (kill) process 000111AF. Use the STOP
command with the /ID flag:
$ STOP /ID=000111AF
Now the file deletion was possible:
$ DEL VMSPO*.*;*
$
The actual cause of the upload failure? I don't have enough quota.
SHOW QUOTA
The sFTP client showed me this error after failing a few times:
550 File Write Error: %%SYSTEM-F-EXDISKQUOTA, disk quota exceeded
This is where my adventure ends. Without looking up documentation, because of the logicalness of DCL, the following command showed me that I had exhausted my disk quota:
$ show quota
User [EXAMPLE] has 10000 blocks used, 0 available,
of 10000 authorized and permitted overdraft of 0 blocks on DISK_USER
What is a disk block you ask? Again the documentation has all the answers:
A disk block is the minimum unit of disk storage allocation in OpenVMS.
Under OpenVMS VAX and OpenVMS Alpha, the disk volume block size is consistent, with each block containing 512 bytes, or one-half kilobyte. Each byte is comprised of eight bits. A bit represents the smallest unit of information, typically refered to as a one or a zero.
[...]
The number of bytes in a file can be determined by multiplying the number of blocks allocated for the file times the number of bytes in a block. For example: to convert OpenVMS disk blocks to (base two) kilobytes (KB; 1024 bytes), simply divide by two. To convert blocks to (base two) megabytes, divide by 2048. Blocks to (base two) gigabytes (GB), divide by 2097152.
In the case of the DECUS system, I have about 5 megabytes of quota and my zipped
curl was around 7 MB, explaining the quota error.