Here’s a small collection of basic statistical functions you can use in your shell scripts. This may come in handy when analyzing disk space, system performance, etc.

Average

avg() {
		sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
		ave = sum / c;
		printf("%.0f\n",ave);
	  }'
}

Minimum

min() {
	sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
		c=asort(a);
		print a[1];
	  }'
}

Maximum

max() {
	sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
	    c=asort(a);
		print a[c];
	  }'
}

Median

median() {
	sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
		ave = sum / c;
		if( (c % 2) == 1 ) {
		  median = a[ int(c/2) ];
		} else {
		  median = ( a[c/2] + a[c/2-1] ) / 2;
		}
		OFS="\t";
		print median;
	  }'
}

Sum

sum() {
	sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
		print sum;
	  }'
}

Count

count() {
	sort -n | awk '
	  BEGIN {
		c = 0;
		sum = 0;
	  }
	  $1 ~ /^[0-9]*(\.[0-9]*)?$/ {
		a[c++] = $1;
		sum += $1;
	  }
	  END {
		print c;
	  }'
}

Maximum difference

maxdelta() {
	i=0 ; unset array_a ; unset array_d ; while read line ; do array_a[$i]="$line" ; (( i++ )) ; done
	array_ac=$(echo "scale=0;`echo ${#array_a[*]}`-2"|bc -l)
	for i in `seq 0 $array_ac`
	do
		array_d[$i]=$(echo "scale=0;`echo ${array_a[(( i + 1 ))]}`-`echo ${array_a[i]}`"|bc -l)
		echo ${array_d[$i]}
	done | max
}

Minimum difference

mindelta() {
	i=0 ; unset array_a ; unset array_d ; while read line ; do array_a[$i]="$line" ; (( i++ )) ; done
	array_ac=$(echo "scale=0;`echo ${#array_a[*]}`-2"|bc -l)
	for i in `seq 0 $array_ac`
	do
		array_d[$i]=$(echo "scale=0;`echo ${array_a[(( i + 1 ))]}`-`echo ${array_a[i]}`"|bc -l)
		echo ${array_d[$i]}
	done | min
}

Average difference

avgdelta() {
	i=0 ; unset array_a ; unset array_d ; while read line ; do array_a[$i]="$line" ; (( i++ )) ; done
	array_ac=$(echo "scale=0;`echo ${#array_a[*]}`-2"|bc -l)
	for i in `seq 0 $array_ac`
	do
		array_d[$i]=$(echo "scale=0;`echo ${array_a[(( i + 1 ))]}`-`echo ${array_a[i]}`"|bc -l)
		echo ${array_d[$i]}
	done | avg
}

Standard Deviation

stddev() {
	awk '{sum+=$1; sumsq+=$1*$1} END {printf("%.2f\n", sqrt(sumsq/NR - (sum/NR)**2))}'
}

Linear Regression

fitline() {
	awk '
	BEGIN { FS = "[ ,\t]+" }
	NF == 2 { x_sum += $1
			  y_sum += $2
			  xy_sum += $1*$2
			  x2_sum += $1*$1
			  num += 1
			  x[NR] = $1
			  y[NR] = $2
			}
	END { mean_x = x_sum / num
		  mean_y = y_sum / num
		  mean_xy = xy_sum / num
		  mean_x2 = x2_sum / num
		  slope = (mean_xy - (mean_x*mean_y)) / (mean_x2 - (mean_x*mean_x))
		  inter = mean_y - slope * mean_x
		  for (i = num; i > 0; i--) {
			  ss_total += (y[i] - mean_y)**2
			  ss_residual += (y[i] - (slope * x[i] + inter))**2
		  }
		  r2 = 1 - (ss_residual / ss_total)
		  printf("Slope      :  %.2f\n", slope)
		  printf("Intercept  :  %.2f\n", inter)
		  printf("R-Squared  :  %.2f\n", r2)
		}'
}

Greatest common denominator

gcd() {
	dividend=
	divisor=
	remainder=1
	until [ "${remainder}" -eq 0 ]
	do
		let "remainder = $dividend % $divisor"
		dividend=${divisor}
		divisor=${remainder}
	done
	echo "${dividend}"
}

Least common multiple

lcm() {
	count=$#
	k=1
	a=
	while [[ $# -gt 0 ]]
	do
		if [[ $1 > $2 ]]
		then
			a=
		fi
		b[${k}]=$1
		k=${k}+1
		shift
	done
	
	lcm=0
	for (( c=9; c>${count}; c-- ))
	do
		b[${c}]=1
	done
	
	for (( i=${a}; i>=${a}; i++ ))
	do
		if (( $(($i % ${b[1]})) == 0 && $(($i % ${b[2]})) == 0 && $(($i % ${b[3]})) == 0 && $(($i % ${b[4]})) == 0 && $(($i % ${b[5]})) == 0 && $(($i % ${b[6]})) == 0 && $(($i % ${b[7]})) == 0 && $(($i % ${b[8]})) == 0 && $(($i % ${b[9]})) == 0 ))
		then
			echo "${i}"
			break         
		fi
	done
}