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The MIDAS odbedit utility is primarily an Online Database (ODB) Editor. It also acts as a run control and has limited run monitoring features, so is an alternative to the web-based run control program mhttpd. On the other hand, the mhttpd ODB Page is more user-friendly, but has limited editing capability and does not support all of the features of odbedit.


The features of odbedit include

  • create the ODB of the desired size
  • edit/list/create/rename/re-order/delete ODB keys
  • create (soft)links to ODB keys
  • save all or part of the ODB onto disk and reload from a saved file
  • start/stop runs
  • list and shutdown active clients
  • create a c-structure from the ODB
  • change a key's access mode (e.g. read-only)
  • execute a list of odbedit commands from a file
  • connect to corrupted ODB

odbedit treats the hierarchical online database very much like a file system. Most commands are similar to UNIX file commands, e.g. ls, cd, chmod, ln etc. The help command displays a short description of all commands.

The odbedit commands and mode of operation are described fully in the following sections.


   [-h hostname ]     : see common parameters 
   [-e exptname ]     : see  common parameters 
   [-c command ]      : Perform a single command. See using an external command
   [-c @commandFile ] : Perform commands in sequence found in the commandFile. See using an external command file
   [-s size ]         : Size in bytes (for ODB creation). See creating the ODB.
   [-d ODB Subtree]   : Specify the initial entry ODB path to go to. See Specifying the ODB entry path.
   [-g ]              : Debug
   [-C ]              : Connect to corrupted ODB
   [-R ]              : Reload ODB from .ODB.SHM


For convenience many users (including the author) make a symlink odb to call odbedit.
 cd $MIDASSYS/linux/bin
 ln -s odbedit odb

Therefore some of the examples in this document start odbedit with the symlink odb


for example here.

Command Line Interpreter

ODBedit has a simple command line interface with command line editing similar to the UNIX tcsh shell. The following edit keys are implemented:

[Backspace]          Erase the character left from cursor
[Delete/Ctrl-D]      Erase the character under cursor
[Ctrl-W/Ctrl-U]      Erase the current line
[Ctrl-K]             Erase the line from cursor to end
[Left arrow/Ctrl-B]  Move cursor left
[Right arrow/Ctrl-F] Move cursor right
[Home/Ctrl-A]        Move cursor to beginning of line
[End/Ctrl-E]         Move cursor to end of line
[Up arrow/Ctrl-P]    Recall previous command
[Down arrow/Ctrl-N]  Recall next command
[Ctrl-F]             Find most recent command which starts with current line
[Tab/Ctrl-I]         Complete the path. The command ls /Sy <tab> becomes ls /System.

Creating the ODB

When odbedit is started for the first time for a Midas experiment, if there is no existing ODB for that experiment, the ODB will be created with the default size of 128KB, unless overruled by the odbedit -s <size> argument, e.g.

odbedit -s 2049000

Using an external command

In the simplest case, a single odbedit command can be entered on the command line using the -c argument, e.g.

$ odbedit -c start
Starting run #401
Run #401 started
$ odbedit -c stop
Run #401 stopped


 $ odbedit -c 'set "/logger/write data" n'
 $ odbedit -c 'ls -v "/logger/write data" '

This external command feature allows for sophisticated shell scripts to be created that can manipulate the odb. See accessing the ODB from a script for more information.

This feature can be used in various scripts - see ODB Access and Use#Accessing the ODB from a script for more information.

Using an external command file

Perform odbedit commands in sequence found in the specified command file e.g.

[pol@isdaq01 pol]$ odbedit -d /Equipment/TDC/Settings/ -c @testfile.com 

where the file "testfile.com" contains odbedit commands, such as

set testval 4 
ls testval

Specifying the initial ODB entry path

The odbedit -d argument is used in conjunction with the -c argument to specify the initial path, e.g.

[pol@isdaq01 pol]$ odbedit -d /test -c "set testval 3"
[pol@isdaq01 pol]$ odb
[local:pol:S]/>ls test

Changing the prompt

The format of the odbedit prompt can be changed. See format of the odbedit prompt.

odbedit command list

Click above link for list of odbedit commands and examples.