It is actually executing the command, changing the directory to some_directory
, however, this is performed in a sub-process shell, and affects neither make nor the shell you’re working from.
If you’re looking to perform more tasks within some_directory
, you need to add a semi-colon and append the other commands as well. Note that you cannot use new lines as they are interpreted by make as the end of the rule, so any new lines you use for clarity need to be escaped by a backslash.
For example:
all:
cd some_dir; echo "I'm in some_dir"; \
gcc -Wall -o myTest myTest.c
Note also that the semicolon is necessary between every command even though you add a backslash and a newline. This is due to the fact that the entire string is parsed as a single line by the shell. As noted in the comments, you should use ‘&&’ to join commands, which means they only get executed if the preceding command was successful.
all:
cd some_dir && echo "I'm in some_dir" && \
gcc -Wall -o myTest myTest.c
This is especially crucial when doing destructive work, such as clean-up, as you’ll otherwise destroy the wrong stuff, should the cd
fail for whatever reason.
A common usage, though, is to call make in the subdirectory, which you might want to look into. There’s a command-line option for this, so you don’t have to call cd
yourself, so your rule would look like this
all:
$(MAKE) -C some_dir all
which will change into some_dir
and execute the Makefile
in that directory, with the target “all”. As a best practice, use $(MAKE)
instead of calling make
directly, as it’ll take care to call the right make instance (if you, for example, use a special make version for your build environment), as well as provide slightly different behavior when running using certain switches, such as -t
.
For the record, make always echos the command it executes (unless explicitly suppressed), even if it has no output, which is what you’re seeing.