A mix of [s6-envdir](https://skarnet.org/software/s6/s6-envdir.html) and [importas](https://skarnet.org/software/execline/importas.html). Reads files containing variable assignments in the given *file/directory*, adds the variables to the environment and then executes a program.
## Interface
```
execl-envfile [ -h ] [ -l ] src prog
```
This tool expects to find a regular file or a directory in *src* containing one or multiple `key=value` pair(s). It will parse that file, import the `key=value` and then exec the given *prog* with the modified environment. In case of directory for each file found it apply the same process. *src* can be an absolute or a relative path.
- It opens and reads a file.
- It parses that file.
- It imports the found `key=value` pair(s).
- It substitutes each corresponding *key* with value from that file.
- It unexports the variable(s) if requested.
- It execs *prog* with the modified environment.
## Exit codes
-*0* success
-*100* wrong usage
-*111* system call failed
## Options
-**-h** : prints this help.
-**-l** : loose; do nothing and execute *prog* directly if *src* does not contain any regular file(s) or *src* does not exist.
## File syntax
*src* is a text file or a directory containing lines of pairs with the syntax being: `key = value`
Whitespace is permitted before and after *key*, and before or after *value*. Quoting is also possible.
Empty lines or lines containing only whitespace are ignored. Lines beginning with `#` (also after whitespace) are ignored and typically used for comments. Comments are not possible at the end of lines: `key = value # comment` is not a valid comment.
If val begin by a `!` character: `key=!value` the key will be removed from the environment after the substitution.
## Usage example
```
#!/usr/bin/execlineb -P
fdmove -c 2 1
execl-envfile %%service_admconf%%/ntpd
foreground { mkdir -p -m 0755 ${RUNDIR} }
execl-cmdline -s { ntpd ${CMD_ARGS} }
```
The equivalent with s6-envdir and importas would be:
```
#!/usr/bin/execlineb -P
fdmove -c 2 1
s6-envdir %%service_admconf%%
importas -u RUNDIR RUNDIR
importas -u CMD_ARGS CMD_ARGS
foreground { mkdir -p -m 0755 ${RUNDIR} }
execl-cmdline -s { ntpd ${CMD_ARGS} }
```
where `%%service_admconf%%` contains two named files `RUNDIR` and `CMD_ARGS` written with `/run/openntpd` and `-d -s` respectively.
## Limits
*src* can not exceed more than `100` files. Each file can not contain more than `4095` bytes or more than `50``key=value` pairs.
