File locking, grep and process killing on OpenVMS
Published: 06-05-2018 | Author: Remy van Elst | Text only version of this article
Table of Contents
(You can read all my OpenVMS articles by clicking the picture above)
On the DECUS OpenVMS system there is no
wget installed. Iwanted to download a remote
C file to play around with the compiler and somesimple
Hello World code, to get a feel of the build system. After a bit ofsearching around the internet I was not able to find a command like curl or wgetto 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 linuxsystem, 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 alocked file to a process, grep the output of a process on OpenVMS and kill aprocess. I did not get curl to work or compile my code, yet.
cc command is installed on the DECUS system:
$ CC /VERSIONHP 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 smallarticle on it here.
I downloaded the OpenVMS curl version from the vmsports project to mycomputer. This is a project that compiles some software for OpenVMS, like
python and the one I was looking for,
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. Butit was too late already, plus, I did learn new stuff in the process. As Bob Rosswould say,
We don't make mistakes, just happy little accidents.
Filezilla however did complain and kept uploading the file. I closed Filezillaand went to check what was wrong via SSH. The file was there, leaving 5versions. 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 mightneed to look into it some more.
I remembered something about locking when reading
HELP pages earlier. In thiscase, 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 SET FILE /UNLOCKSET 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 processwhich locked my file.
Tracing a process' open files (lsof)
The HPe forums where of help here. First I needed the root disk name, which isin the
$ DIRDirectory DSA3:[DECUSERVE_USER.EXAMPLE]$MAIN.TPU$JOURNAL;1 .VIMINFO;1 A.;1 FTP_SERVER.LOG;3FTP_SERVER.LOG;1 LOGIN.COM;2 LOGIN.COM;1 LOGIN_COM.TPU$JOURNAL;1MAIL.DIR;1 NOTES$NOTEBOOK.NOTE;1 SSH.DIR;1SSH2.DIR;1 THREE.DIR;1 VMSPORTS-AXPVMS-83-CURL-V0747--1.ZIP;1WWW.DIR;1
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 10:31:44.88Process name PID File name 00000000 insufficient privilege or object protection violation 00000000 insufficient privilege or object protection violationRob Brooks 0000043B insufficient privilege or object protection violationHENKLE 0000F62B insufficient privilege or object protection violationHENKLE 0000F62B insufficient privilege or object protection violationHENKLE 0000F62B insufficient privilege or object protection violationHENKLE 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 lockedmy file. One of the ways to release that lock is to stop the process. Anotherway is to reboot the system. The latter being a harsh solution if all elsefails.
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 allthose other users, none of my business. I wanted to filter that list to onlyshow 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 wantto 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.
search command requires a filename. You can't just pipe output into itdirectly, you need to tell it that it has to search the output. OpenVMS has the
SYS$INPUT files for that when using the
Reading through the documentation:
|: Key pipe separator. The pipe connects the
SYS$OUTPUTof one pipeline-segment command to the
SYS$INPUTof the next command.
A few tries later I conjured up this command sequence:
$ PIPE SHOW DEV /FILES DSA3: | SEARCH SYS$INPUT EXAMPLEFiles accessed on device DSA3: on 6-MAY-2018 12:48:11.51Process 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 SYSTEMcommand. Combine that with out
PIPE&SEARCH shell trick to get all theprocesses of the current user. Searching the docs didn't gave me anotherway or flag to the
SHOW SYSTEM or
SHOW PROCESS command to filter out onespecific user.
$ PIPE SHOW SYSTEM | SEARCH SYS$INPUT EXAMPLEOpenVMS 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 89000111AF <FTP_EXAMPLE> LEF 5 46299 0 00:00:06.01 705 346 N000115B0 EXAMPLE_62273 LEF 6 129 0 00:00:00.01 84 105 S000115BE EXAMPLE_27501 CUR 0 4 188 0 00:00:00.04 138 165 S000115BF 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
STOPcommand with the
$ STOP /ID=000111AF
Now the file deletion was possible:
$ DEL VMSPO*.*;*$
The actual cause of the upload failure? I don't have enough 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 ofthe logicalness of DCL, the following command showed me that I had exhausted mydisk 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.