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Diffstat (limited to 'doc/src/guide/escripts.asciidoc')
-rw-r--r-- | doc/src/guide/escripts.asciidoc | 72 |
1 files changed, 70 insertions, 2 deletions
diff --git a/doc/src/guide/escripts.asciidoc b/doc/src/guide/escripts.asciidoc index 3d68c77..eebd6d8 100644 --- a/doc/src/guide/escripts.asciidoc +++ b/doc/src/guide/escripts.asciidoc @@ -1,6 +1,74 @@ [[escript]] == Escripts -// @todo Write it. +Escripts are an alternative to release. They are meant to be +used for small command line executables written in Erlang. -Placeholder chapter. +They are not self-contained, unlike xref:relx[releases]. +Erlang must be installed for them to run. This however means +that they are fairly small compared to releases. + +For self-contained executables, check xref:sfx[self-extracting releases]. + +Erlang.mk uses `p7zip` by default to generate the escript +archive. Make sure it is installed. + +=== Generating an escript + +Run the following command to generate an escript: + +[source,bash] +$ make escript + +This will by default create an escript with the same name as +the project, in the project's directory. If the project is +called `relx` then the escript will be in `./relx`. + +You can run the escript as you would any executable: + +[source,bash] +$ ./relx + +=== Configuration + +You can change the name of the escript by setting `ESCRIPT_NAME`. +The name determines both the default output file name and the +entry module containing the function `main/1`. + +`ESCRIPT_FILE` can be set if you need a different file name +or location. + +The escript header can be entirely customized. The first line +is the shebang, set by `ESCRIPT_SHEBANG`. The second line is +a comment, set by `ESCRIPT_COMMENT`. The third line is the +arguments the VM will use when running the escript, set by +`ESCRIPT_EMU_ARGS`. + +Finally, `ESCRIPT_ZIP` can be set to customize the command used +to create the zip file. Read on for more information. + +=== Extra files + +Generating an escript is a two-part process. First, a zip file +is created with the contents of the escript. Then a header is +added to this file to create the escript. + +It is possible to add commands that will be executed between +the two steps. You can for example add extra files to the zip +archive: + +[source,make] +---- +escript-zip:: + $(verbose) $(ESCRIPT_ZIP) $(ESCRIPT_ZIP_FILE) priv/templates/* +---- + +The `ESCRIPT_ZIP` variable contains the command to run to add +files to the zip archive `ESCRIPT_ZIP_FILE`. + +=== Optimizing for size + +Erlang.mk will by default compile BEAM files with debug +information. You may want to disable this behavior to obtain +smaller escript files. Simply set `ERLC_OPTS` to a value that +does not include `+debug_info`. |