--- name: "lslk" section: "8" platform: "linux" package: "lslk" version: "1.29-6" release: "Debian 6.0 (Squeeze)" platforms: ["linux"] url: "https://new.carta.tech/lslk" --- # lslk(8) list local locks ## NOTICE ``` !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!!! ! ! ! Revision 1.29 represents the end of life for lslk. I don't have time ! ! to support it. Please don't report bugs to me. I will politely ! ! decline to work on them. ! ! ! ! Vic Abell , July 11, 2001 ! ! ! !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!! !!!NOTICE!!!! ``` ## NAME lslk - list local locks ## SYNOPSIS **lslk** \[ **-abhnOvw** \] \[ **-i** *i* \] \[ **-k** *k* \] \[ **-p** *p* \] \[ **-S** *\[t\]* \] \[ *paths* \] ## DESCRIPTION *Lslk* revision 1.29 lists information about locks held on files with local inodes on systems running the following UNIX dialects: ``` AIX 3.2.5, 4.1.4, 4.2[.1], and AIX 4.3[.[12]] DEC OSF/1, Digital UNIX, and Tru64 UNIX [2345].[01] and 3.2 Linux SCO OpenDesktop or OpenServer 3.0 and 5.0.[0245] Sequent PTX 2.1.9, 4.2.1, 4.3, and 4.4 Solaris 2.[345], 2.5.1, 2.6, 7, and 8 (excluding Veritas VxFS local files) SunOS 4.1.3 ``` The lock may belong to a process on the local system or to a process on an NFS client system to which the local system is an NFS server. Notes: Linux and PTX 2.1.9 *lslk* don't report on locks held by NFS clients; Solaris *lslk* won't report locks held on local Veritas VxFS files. ## OPTIONS In the absence of any options, *lslk* lists all locks associated with the local files of the system. When selection options are specified, the listing of all locks is disabled, and the selection options are ORed together. Only locks meeting any selection criterion are listed. When the **-a** option is specified, the listing of all locks is disabled, and the selection options are ANDed together. Only locks that meet all selection criteria are listed. - **-a** This option causes list selection options to be ANDed, as described above. - **-b** This option causes *lslk* to avoid kernel functions that might block - [*lstat*(2)](/lstat/2.md), [*readlink*(2)](/readlink/2.md), and [*stat*(2)](/stat/2.md). - See the **BLOCKS AND TIMEOUTS** and **AVOIDING KERNEL BLOCKS** sections for information on using this option. - **-i** *i* This option selects the listing of locks whose owning process is on the Internet host whose name or network address is *i*. - Multiple addresses may be declared with multiple **-i** *i* options. - **-k** *k* This option specifies *k* as an alternate to the default kernel name list file path. The default kernel name list file path is listed in the **-h** help output. - It may be necessary to specify an alternate kernel name list path when the file at the default path isn't the booted kernel -- e.g., the default is */vmunix*, but the booted kernel file is */vmunix.new*. - Unless *lslk* accesses the correct kernel name list file, it may derive incorrect addresses for symbols in kernel memory, causing it to fail. - **-n** This option inhibits the conversion of network host names to network addresses and the conversion of network addresses to network host names. - This option may be useful when the host name to address translation service (e.g., the Domain Name Server) is slow or inoperative. - If you use this option on hosts whose kernel lock table contains only host names - e.g., SCO or Solaris - or you use this option and also select the listing of locks by an Internet network address with the **-i** *i* option, *lslk* will not be able to locate any locks with the specified network address, nor will it be able to report network addresses in its output. The **-n** option inhibits the necessary conversion of kernel lock table host names to network addresses. - **-O** This option directs *lslk* to bypass the strategy it uses to avoid being blocked by some kernel operations - i.e., doing them in forked child processes. See the **BLOCKS AND TIMEOUTS** and **AVOIDING KERNEL BLOCKS** sections for more information on kernel operations that may block *lslk*. - **-p** *p* This option selects the listing of locks whose owning process IDentification (PID) numbers are in the comma-separated list, *p*. - **-S** *\[t\]* This option specifies an optional time-out seconds value for kernel functions - [*lstat*(2)](/lstat/2.md), [*readlink*(2)](/readlink/2.md), and [*stat*(2)](/stat/2.md) - that might otherwise deadlock. The minimum for *t* is two; the default, fifteen; when no value is specified, the default is used. - See the **BLOCKS AND TIMEOUTS** section for more information. - **-v** When this option is specified, *lslk* lists version information - i.e., where, when and how it was constructed. - **-w** This option suppresses non-fatal warning messages. - *paths* This option specifies a list of file path names for which *lslk* is to list lock information. ## OUTPUT *Lslk* lists the information for each lock on a separate line in the following columns. (The columns are dynamically sized.) - SRC indicates the source of the process holding the lock. - If the source is a local process, its command name is displayed, or \`\`(unknown)'' if the command name can't be determined. - If the source is a remote process, the host name or network number where the remote process executes is displayed. - PID is the Process IDentification number of the process holding the lock. - DEV is the device (major and minor numbers) on which the locked file resides. - INUM is the inode number of the locked file. - SZ is the size of the locked file. - TY is the lock type: ``` r read; rw read and write; w write; ? unknown. ``` - M is the mandatory state of the lock: 0 if none; 1 if set. (See [*chmod*(1)](/chmod/1.md)). - ST is the relative byte offset of the lock. - WH is the starting offset (\`\`whence'') of the lock. - END is the ending offset of the lock. - LEN is the length of the lock. - NAME is the name of the locked file, if it was specified as a *path* argument. - If there is no *path* argument name, then the mount point and device paths of the file system on which the locked file resides are displayed. ## BLOCKS AND TIMEOUTS *Lslk* can be blocked by some kernel functions that it uses - [*lstat*(2)](/lstat/2.md), [*readlink*(2)](/readlink/2.md), and [*stat*(2)](/stat/2.md). These functions are stalled in the kernel, for example, when the hosts where mounted NFS file systems reside become inaccessible. *Lslk* attempts to break these blocks with timers and child processes, but the techniques are not wholly reliable. When *lslk* does manage to break a block, it will report the break with an error message. The messages may be suppressed with the **-w** option. The default timeout value may be displayed with the **-h** option, and it may be changed with the **-S** *\[t\]* option. The minimum for *t* is two seconds, but you should avoid small values, since slow system responsiveness can cause short timeouts to expire unexpectedly and perhaps stop *lslk* before it can produce any output. When *lslk* has to break a block during its access of mounted file system information, it normally continues, although with less information available to display about open files. *Lslk* can also be directed to avoid the protection of timers and child processes when using the kernel functions that might block by specifying the **-O** option. While this will allow *lslk* to start up with less overhead, it exposes *lslk* completely to the kernel situations that might block it. Use this option cautiously. ## AVOIDING KERNEL BLOCKS You can use the **-b** option to tell *lslk* to avoid using kernel functions that would block. Some cautions apply. First, using this option usually requires that your system supply alternate device numbers in place of the device numbers that *lslk* would normally obtain with the [*lstat*(2)](/lstat/2.md) and [*stat*(2)](/stat/2.md) kernel functions. See the **ALTERNATE DEVICE NUMBERS** section for more information on alternate device numbers. Second, you can't specify the *names* of files you want *lslk* to locate locks for unless they're file system names. This is because *lslk* needs to know the device and inode numbers of files listed with *names* in the *lslk* options, and the **-b** option prevents *lslk* from obtaining them. Moreover, since *lslk* only has device numbers for the file systems that have alternates, its ability to locate locks on file systems depends completely on the availability and accuracy of the alternates. If no alternates are available, or if they're incorrect, *lslk* won't be able to locate locks on the named file systems. Third, if the names of your file system directories that *lslk* obtains from your system's mount table are symbolic links, *lslk* won't be able to resolve the links. This is because the **-b** option causes *lslk* to avoid the kernel [*readlink*(2)](/readlink/2.md) function it uses to resolve symbolic links. Finally, using the **-b** option causes *lslk* to issue warning messages when it needs to use the kernel functions that the **-b** option directs it to avoid. You can suppress these messages by specifying the **-w** option, but if you do, you won't see the alternate device numbers reported in the warning messages. ## ALTERNATE DEVICE NUMBERS On some dialects, when *lslk* has to break a block because it can't get information about a mounted file system via the [*lstat*(2)](/lstat/2.md) and [*stat*(2)](/stat/2.md) kernel functions, or because you specified the **-b** option, *lslk* can obtain some of the information it needs - the device number and possibly the file system type - from the system mount table. When that is possible, *lslk* will report the device number it obtained. (You can suppress the report by specifying the **-w** option.) You can assist this process if your mount table is supported with an */etc/mtab* or */etc/mnttab* file that contains an options field by adding a \`\`dev=xxxx'' field for mount points that do not have one in their options strings. The \`\`xxxx'' portion of the field is the hexadecimal value of the file system's device number. (Consult the *st\_dev* field of the output of the [*lstat*(2)](/lstat/2.md) and [*stat*(2)](/stat/2.md) functions for the appropriate values for your file systems.) Here's an example from a Solaris 2.5 */etc/mnttab* for a UFS file system: ``` ... ufs suid,rw,dev=80001f ... ``` Some dialects that do not use an ASCII */etc/mtab* or */etc/mnttab* file for the mount table may still provide an alternative device number in their internal mount tables. This includes AIX, DEC OSF/1, Digital UNIX, and Tru64 UNIX. *Lslk* knows how to obtain the alternative device number for these dialects and uses it when its attempt to [*lstat*(2)](/lstat/2.md) or [*stat*(2)](/stat/2.md) the file system is blocked. If you're not sure your dialect supplies alternate device numbers for file systems from its mount table, use this *lslk* incantation to see if it reports any alternate device numbers: - lslk -b Look for standard error file warning messages that begin \`\`assuming "dev=xxxx" from ...''. ## DIAGNOSTICS Errors are identified with messages on the standard error file. *Lslk* returns a one (1) if an error was detected or if it couldn't list lock information for all the *names* that were specified. ## EXAMPLES To list all locks, use: - lslk To list locks from the host \`\`klaatu'' in the local domain, use: - lslk -i klaatu To list locks from the hosts helios.cc.purdue.edu and vic1.cc.purdue.edu, use: - lslk -i helios.cc.purdue.edu -i vic1.cc.purdue.edu To list locks held by processes 1234 and 56789, use: - lslk -p 1234,56789 To list all locks held by process 1234 on host klaatu, use: - lslk -p 1234 -a -i klaatu ## PERMISSION *Lslk* must have permission to access the system memory files - e.g., */dev/kmem* and */dev/mem*. Permission to do that is granted when the *lslk* process is run from a root shell, or when its \`\`setgid'' group matches the group (e.g., \`\`sys'') that can read the system memory files. ## BUGS Perhaps it should be possible to specify the host on which a search target PID is located. DEC OSF/1, Digital UNIX, and Tru64 UNIX *lslk* won't find locks applied with the [*flock*(2)](/flock/2.md) function. It will find locks applied with the [*fcntl*(2)](/fcntl/2.md) and [*lockf*(3)](/lockf/3.md) functions. Linux *lslk* will not report locks held by NFS clients. It may have difficulty reporting locks held on dynamic inodes (e.g., for the Win-95 file system type, *smbfs*). - Solaris *lslk* won't find locks held on local Veritas VxFS files by local or remote processes. ## FILES - */dev/kmem* kernel virtual memory device - */dev/mem* physical memory device ## AUTHORS *Lslk* was written by Victor A. Abell \ of the Purdue University Computing Center (PUCC). Chris Eleveld \ did the DEC OSF/1, Digital UNIX, Linux, and Tru64 UNIX ports. ## SEE ALSO [chmod(1)](/chmod/1.md), [fcntl(2)](/fcntl/2.md), fcntl(5), flock(3B), lockd(1M), [lstat(2)](/lstat/2.md), lockf(3C), [readlink(2)](/readlink/2.md), [stat(2)](/stat/2.md).