---
name: "lamhalt"
section: "1"
platform: "linux"
package: "lam-runtime"
version: "7.1.4-7.2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/lamhalt"
---

# lamhalt(1)

Shutdown the LAM/MPI run-time environment.

## NAME

lamhalt - Shutdown the LAM/MPI run-time environment.

## SYNOPSIS

lamhalt \[-dhHv\]

## OPTIONS

- **-d**

  Turn on debugging mode.  This implies -v.

- **-h**

  Print the command help menu.

- **-i**

  Return immediately (even before the LAM universe is fully halted); deprecated

- **-H**

  Suppress printing the header message.

- **-v**

  Be verbose.

## DESCRIPTION

The *lamhalt* tool terminates the LAM software on each of the nodes that were initially booted with *lamboot* and/or  *lamgrow*. No additional command line arguments are necessary -  *lamhalt* simply sends a message to each remote node telling it to shut down. Each remote node invokes [tkill(1)](/tkill/1.md) locally to shut down.  See [tkill(1)](/tkill/1.md) for a description of how LAM is terminated on each node.

*lamhalt* may fail if one of the remote nodes has failed, and does not respond to *lamhalt*'s queries.  In this case, the [lamwipe(1)](/lamwipe/1.md) command should be used to shut down LAM/MPI.  If [lamwipe(1)](/lamwipe/1.md) fails, the user can manually invoke [tkill(1)](/tkill/1.md) on the troubled node.  In extreme cases, the user may have to terminate individual LAM processes with [kill(1)](/kill/1.md).

Older versions of *lamhalt* would return 1-3 seconds before the entire LAM universe was shut down.  This caused problems for some LAM users, particularly those who had scripts that invoked *lamboot* immediately after *lamhalt*. *lamhalt* has therefore been changed to wait until the entire LAM universe is down before exiting.  This makes the execution of *lamhalt* take a few seconds (typically less than 5).

For users who want the old  *lamhalt* behavior, use the  *-i* (or "immediate") switch, which will cause *lamhalt to return immediately, likely before the entire LAM* universe has been taken down.

## EXAMPLES

- lamhalt -d

  Shutdown LAM on the machines and be verbose about its actions.

## SEE ALSO

[recon(1)](/recon/1.md), [lamboot(1)](/lamboot/1.md), [tkill(1)](/tkill/1.md), [bhost(5)](/bhost/5.md), [lam-helpfile(5)](/lam-helpfile/5.md), [lamwipe(1)](/lamwipe/1.md)