Linux
In Linux, you can just run this in Terminal:
msgcat yourFile.po | msgfmt -o generatedFile.mo -
or
msgfmt -o generatedFile.mo yourFile.po
You can view more information about these commands by typing:
man msgcat
man msgfmt
Mac OS X
You can get msgcat/msgfmt (as above) either with Xcode or with brew install gettext.
However, it will not add them to your path to avoid conflict with OS X’s own gettext utility (says homebrew). You can either add it anyway by adding this to your bash_profile:
export PATH=${PATH}:/usr/local/opt/gettext/bin
Or otherwise if you only need msgcat/msgfmt you can use aliases. Just add these lines to your bash_profile:
msgcat="/usr/local/opt/gettext/bin/msgcat"
msgfmt="/usr/local/opt/gettext/bin/msgfmt"
Hope this helps! (Thanks to Georgi Stoyanov!)
Windows
On windows you can install MinGW (Minimal GNU for Windows) you need to select mingw32-gettext (bin and dev) durring installation and msgfmt and msgcat exe files will be installed. By default in c:\MinGW\bin. In order to use this tools you need to add that directory to your PATH variable. You can do that from command line using:
set PATH=%PATH%;c:\MinGW\bin
or from Control Panel > System and Security > System > Advanced System Settings > Environment Variables.