The s6-frontend-config-preprocess program

s6-frontend-config-preprocess reads a s6-frontend configuration file and executes all its inclusion directives, also preprocessing the included files. It streams the result to stdout, which is a complete configuration file without inclusions.

Interface

     s6-frontend-config-preprocess file

s6-frontend-config-preprocess reads file and prints it to stdout. It removes lines starting with !!.

When it finds a !include or !includeonce directive in file, it replaces it with the contents of the included file - recursively preprocessed.

When it finds a !includedir or !includedironce directive in file, it replaces it with the recursively preprocessed contents of every file present in the included directory. The files are sorted alphabetically according to the C locale.

!includeonce and !includedironce only print a file (resp. a directory) the first time they encounter it, and silently ignore subsequent instances. !include and !includedir directives will happily include the same files several times.

To avoid loops, a nesting limit exists. s6-frontend-config-preprocess will fail if there are too many nested inclusions.

Exit codes

0: success
1: syntax error in a configuration file
2: other error in a configuration file
3: too many nested inclusions
100: usage error
111: system call failed

Notes

s6-frontend-config-preprocess is not meant to be called directly by the user. It is normally invoked by s6-frontend-config-parse. However, the binary is made available for debugging purposes.