shell

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pwd > /dev/null 2>&1
add(){ return $[$1+$2];}
add 1 2
echo $?
if [ `expr 2 \* 2` -eq $((2 + 2)) -a 1 -lt 2 -a $[1+1] -ge 2 ]; then echo `date`; fi
echo [email protected]
arr=({0..9})
echo ${#arr[@]}
echo {a..z} | sed 's/ //g'
for x in `echo {-5..5}`; do echo $x; done