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I have read this interesting post regarding the installation of php-mongo driver not writeable by the current user

mkdir pear
ln -s pear /tmp/pear-build-`whoami`
/usr/bin/pear config-set cache_dir $HOME/pear/cache
/usr/bin/pear config-set download_dir $HOME/pear/download
/usr/bin/pear config-set temp_dir $HOME/pear/temp

This makes pear compile it in your home directory instead of /tmp.

Then I ran:

pecl install mongo

What is the outcome of running the following command?

ln -s pear /tmp/pear-build-`whoami`
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A command surrounded by back-ticks is replaced by its output. So `whoami` gets replaced by david on my computer. (To see more information on whoami, run man whoami.)

So this command:

ln -s pear /tmp/pear-build-`whoami`

gets turned into this (depending on your username):

ln -s pear /tmp/pear-build-david

ln is a command to create hard links or symbolic links. The -s flags indicates that it will create a symbolic link pointing to pear. Its own filename is /tmp/pear-build-david.

I'm not sure why this step is necessary for pear, as it depends on how pear works internally.

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