Image location: http://autobuilder.yoctoproject.org/pub/nightly/20121226-1/
Tree/Branch: poky/master
Git commit: 4a36a32567ecfbc7ce7b967803e6e23314953ef5

The procps package which includes ps command is missing in sato and sato-sdk image. Currently the /bin/ps command is linked to busybox. 
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root@qemuarm:~# ls -l /bin/ps
lrwxrwxrwx    1 root     root             7 Dec 26 20:35 /bin/ps -> busybox
root@qemuarm:~# 
root@qemuarm:~# rpm -qf /bin/ps
busybox-1.20.2-r4.armv5te
root@qemuarm:~# 
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With 20121205 build (git commit: 381c4b69c7e8b452f4d3de2f8214e6e5f6a9abe7), This package is installed.
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root@qemuarm:~# ls -l /bin/ps
lrwxrwxrwx    1 root     root             9 Dec  5 18:05 /bin/ps -> ps.procps
root@qemuarm:~# rpm -qf /bin/ps.procps 
procps-3.2.8-r10.armv5te
root@qemuarm:~# 
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I don't know if it is a real issue or we just do it on purpose.