On my first run of minecraft after an operation system reinstall, I got this output to the console. Seems to be unintended debug output. Probably the "asdf" and the uncaught FileNotFoundException are separate issues.

thue@Thue-Desktop:~/local/launchers/magiclauncher$ java -jar /home/thue/local/bin/minecraft.jar
asdf
java.io.FileNotFoundException: /home/thue/.minecraft/lastlogin (No such file or directory)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:138)
at net.minecraft.LoginForm.readUsername(LoginForm.java:110)
at net.minecraft.LoginForm.<init>(LoginForm.java:55)
at net.minecraft.LauncherFrame.<init>(LauncherFrame.java:23)
at net.minecraft.LauncherFrame.main(LauncherFrame.java:167)
at net.minecraft.MinecraftLauncher.main(MinecraftLauncher.java:13)