Some basic tricks ::

Convert image to pdf :

convert image1.jpg image1.jpg new.pdf




Find swap space in LINUX:

#swapon -s

or
#vim /proc/swaps
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Finding the no of threads a process has :
#ps -o nlwp <pid of process>

or

#vim /proc/<pid of process>/status | grep Threads
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/bin vs /sbin
/bin - contains banaries like cat,ls,rm etc.
/sbin - also contains binaries with super user priveledges .


Find out no. of times a command has been executed :
#hash