Setting the LD_PRELOAD environment variable for commands run without typing the full path

Question

I'm playing around with LD_PRELOAD and have produced a library that simply wraps puts() in a function that converts the string to be printed to uppercase before printing. I then export the LD_PRELOAD variable as so ``` $ export LD_PRELOAD=/home/adrian/test/myputs.so ``` Now the behaviour works as expected when running the command ``` $ /bin/pwd /HOME/ADRIAN/TEST ``` But it does not work when runing like this ``` $ pwd /home/adrian/test ``` What is the mechanism that's causing the LD_PRELOAD environment variable to be ignored in this case?

Accepted Answer

Because`pwd` is `shell builtin command` - see `man bash` or docs here. So if you write

```
$ pwd
```

Then the builtin command is launched. If you tell it the path, it will execute the ELF binary and use the LD_PRELOAD.

Setting the LD_PRELOAD environment variable for commands run without typing the full path

Solution

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