---
name: "h2root"
section: "1"
platform: "linux"
package: "root"
version: "6.40.04-1"
release: "Arch Linux 2026-11-01"
platforms: ["linux"]
url: "https://new.carta.tech/h2root"
---

# h2root(1)

convert PAW HBOOK files to ROOT files

## NAME

h2root - convert PAW HBOOK files to ROOT files

## SYNOPSIS

**h2root** *file.hbook file.root \[compress\] \[tolower\] \[lrecl\]*

## DESCRIPTION

**h2root** you can use to convert your **HBOOK/PAW** histograms or ntuples files into **ROOT** files. To use this program, you type the shell script command:

**h2root** *hbookfile* *rootfile*

If you do not specify the second parameter, a file name is automatically generated for you. If *hbookfile* is of the form *file.hbook*, then the **ROOT** file will be called *file.root*.

This program converts **HBOOK** histograms into **ROOT** objects of the class *TH1F*. **HBOOK** profile histograms are converted into **ROOT** profile histograms (see class *TProfile*). **HBOOK** row-wise and column-wise ntuples are automatically converted to **ROOT** Trees(see *TTree*). Some **HBOOK** column-wise ntuples may not be fully converted in case one of the columns is an array with fix dimensions (eg. \`var\[6\]') or is a multi-dimensional array.

**HBOOK** integer identifiers are converted into **ROOT** named objects by prefixing the integer identifier with the letter \`h' if the identifier is a positive integer and by \`h\_' if it is a negative integer identifier.

In case of row-wise or column-wise ntuples, each column is converted to a branch of a Tree. **Note that** **h2root** is able to convert **HBOOK** files containing several levels of sub-directories. **Once you have converted your file, you can look at it and draw** histograms or process ntuples using the **ROOT** interactive module. You can also use the **ROOT** browser (see *TBrowser*) to inspect this file.

The chapter *How to read a Tree* explains two ways to read a Tree. ROOT includes the function *TTree::MakeCode* to automatically generate the code for a skeleton analysis function. With

## OPTIONS

- **compress**

  \= 1 by default (use 0 for no compression)

- **tolower**

  \= 1 by default (use 0 to keep case of column names)

- **lrecl**

  \= 0 by default (must be specified if \>8092)

## SEE ALSO

*[root(1)](/root/1.md)*, *[g2root(1)](/g2root/1.md)*

and

*The ROOT Users Guide*

available from the main **ROOT** website:

*http://root.cern*

**h2root** is documented fully on

*http://root.cern/root/HowtoConvert.html*

## ORIGINAL AUTHORS

The ROOT team (see web page above):

**Rene Brun** and **Fons Rademakers**

## COPYRIGHT

This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

## AUTHOR

This manual page was written by Christian Holm Christensen \<cholm@nbi.dk\>, for the Debian GNU/Linux system (but may be used by others).