ospcat Command in Linux
The ospcat command in Linux handles SGML (Standard Generalized Markup Language) catalogs. It helps retrieve effective system identifiers associated with various catalog components, which include entities, public IDs, system IDs, and notations.
The effective system identifiers are the final resolved path or URI used by the system to access a resource after resolving any mappings in catalog files. The ospcat command displays these identifiers to the standard output. Note that the tool does not verify whether they correspond to actual files.
Table of Contents
Here is a comprehensive guide to the options available with the ospcat command −
- Installation of ospcat Command
- Syntax of ospcat Command
- ospcat Command Options
- Examples of ospcat Command in Linux
Installation of ospcat Command
The ospcat command is a part of the OpenSP toolset, to use it, the OpenSP must be installed on Linux.
To install OpenSP on Ubuntu, Kali Linux, Debian, and other Debian-based distributions, use the following command −
sudo apt install opensp
To install it on Arch Linux, use the command given below −
sudo pacman -S opensp
To install it on CentOS, use −
sudo yum install opensp
To install it on Fedora, use the following command −
sudo dnf install opensp
To verify the installation, check the version of the ospcat command −
ospcat --version
Or check the binary path, using the which command −
which ospcat
Syntax of ospcat Command
The syntax of the ospcat command is as follows −
ospcat [options] -c [file]
In the above syntax, the [options] field is used to specify the various options to modify the command’s behavior. The -c [file] is used to specify the catalog file.
ospcat Command Options
The options of the ospcat command are listed below −
| Flags | Options | Description |
|---|---|---|
| -b name | --bctf=name | Use the specified bctf for output |
| -f file | --error-file=file | Append error messages to the specified file |
| -c sysid | --catalog=sysid | Use the specified catalog sysid |
| -C | --catalogs | Treat arguments as catalogs, using the DOCUMENT entry |
| -D directory | --directory=directory | Search for files in the specified directory |
| -R | --restricted | Restrict file reading |
| -P literal | --public-id=literal | Print the system ID for the given public ID literal |
| -S literal | --system-id=literal | Print the system ID for the given system ID literal |
| -p name | --parameter-entity=name | Print the system ID for the given parameter entity |
| -d name | --doctype=name | Print the system ID for the specified document type |
| -l name | --linktype=name | Print the system ID for the specified link type |
| -e name | --entity=name | Print the system ID for the specified entity |
| -n name | --notation=name | Print the system ID for the specified notation |
| -s name | --declaration=name | Print the SGML declaration's system ID for the specified doctype |
| -v | --version | Display the command version |
| -h | --help | Display help text |
Examples of ospcat Command in Linux
In this section, the usage of the ospcat command will be discussed with examples.
The ospcat command relies on an environment variable to locate the catalog file. To set the environment variable, use the following syntax −
export SGML_CATALOG_FILES=/path/to/file
To set the home directory as a catalog file environment variable, use the following command −
export SGML_CATALOG_FILES=/home/user/file.cat
The content of the catalog file used in the following examples is given below −
Displaying System Identifier for Public ID
The -P or --public-id option is used to display the system identifier for public ID.
ospcat -P "-//W3C//DTD HTML 4.01//EN"
Displaying System Identifier for an Entity
To display the system identifier for an entity, use the -e or --entity option.
ospcat -e "logo"
Displaying System Identifier of a Doctype
To display the system ID for a doctype, use the -d or --doctype option with the name −
ospcat -d "book"
Displaying System Identifier for a Notation
To display the system identifier for a notation, use the -n or --notation option −
ospcat -n "PNG"
Displaying SGML Declaration
To display the SGML declaration, use the -s or --declaration option. For example, to display the SGML declaration of PNG notation, use the following command −
ospcat -s "PNG"
Searching Catalog Files is a Specific Directory
To search for files in a specific directory, use the -D or --directory with the directory path −
ospcat -D /etc/sgml/catalog
Restricting the File Access
To restrict the file access, use the -R or --restrict option with the ospcat command −
ospcat -R
The -R or --restrict restricts ospcat from accessing arbitrary files, enhancing security in environments like web applications where file access needs to be controlled.
Displaying Help
To display the help text related to the ospcat command, use the -h or --help option −
ospcat -h
Conclusion
The ospcat command in Linux is part of the OpenSP toolset, used to manage SGML catalogs. It retrieves and displays system identifiers for catalog components such as entities, public IDs, system IDs, notations, and more. The tool does not validate whether the identifiers correspond to actual files. To use ospcat, OpenSP must be installed on the system.
In this tutorial, we explained the ospcat command, its installation, syntax, options, and usage in Linux with examples.