Shell Scripting — Advanced AWK: Mathematical Functions & Formatting

# ── Numeric functions reference ───────────────────────────
awk 'BEGIN {
  # Integer truncation
  print int(3.9)          # 3
  print int(-3.9)         # -3

  # Square root
  print sqrt(2)           # 1.41421

  # Power (x^y)
  print 2^10              # 1024
  print 2**10             # 1024 (gawk)

  # Logarithm / exponent
  print log(2.71828)      # ~1.0 (natural log)
  print exp(1)            # 2.71828

  # Trigonometry (radians)
  pi = atan2(0, -1)       # π = 3.14159...
  print sin(pi/6)         # 0.5
  print cos(0)            # 1.0

  # Absolute value
  print (-5 < 0) ? -(-5) : -5   # 5 (manual abs)

  # Random number 0 <= rand() < 1
  srand(42)               # seed for reproducibility
  print rand()            # reproducible random
  print int(rand() * 100) # random int 0-99
}'

# Compute full statistics in a single pass
awk '
{
  n++
  sum  += $1
  sum2 += $1 * $1
  if (n == 1 || $1 < min) min = $1
  if (n == 1 || $1 > max) max = $1
}
END {
  if (n == 0) { print "No data"; exit }
  mean = sum / n
  var  = (sum2 / n) - (mean * mean)
  sd   = sqrt(var < 0 ? 0 : var)   # guard floating point
  printf "Count:  %d\n",   n
  printf "Sum:    %.3f\n",  sum
  printf "Mean:   %.3f\n",  mean
  printf "Min:    %.3f\n",  min
  printf "Max:    %.3f\n",  max
  printf "StdDev: %.3f\n",  sd
  printf "Range:  %.3f\n",  max - min
}' response_times.txt

# ── Percentiles (requires storing all values) ─────────────
awk '{ vals[NR] = $1 }
END {
  n = asort(vals)
  printf "P50:  %.3f\n", vals[int(n*0.50)]
  printf "P90:  %.3f\n", vals[int(n*0.90)]
  printf "P95:  %.3f\n", vals[int(n*0.95)]
  printf "P99:  %.3f\n", vals[int(n*0.99)]
}' response_times.txt   # gawk: asort() available

# Portable alternative (pipe to sort)
awk '{ print $1 }' response_times.txt | sort -n | awk '
{ vals[NR]=$1 }
END {
  printf "P95: %.3f\n", vals[int(NR*0.95)]
  printf "P99: %.3f\n", vals[int(NR*0.99)]
}'

# ── Bucket response times into ranges ─────────────────────
awk '{
  ms = $1 * 1000   # convert seconds to ms
  if      (ms <  100) bucket["  0-100ms"]++
  else if (ms <  250) bucket["100-250ms"]++
  else if (ms <  500) bucket["250-500ms"]++
  else if (ms < 1000) bucket["500ms-1s "]++
  else if (ms < 2000) bucket["  1s-2s  "]++
  else                bucket["   >2s   "]++
  total++
}
END {
  n = asorti(bucket, sorted)
  for (i=1; i<=n; i++) {
    b = sorted[i]
    pct = bucket[b] / total * 100
    bar = ""
    for (j=0; j access.log

# ── Dynamic bucket width ──────────────────────────────────
awk 'BEGIN { bucket_size = 10 }
{
  b = int($1 / bucket_size) * bucket_size
  label = sprintf("%d-%d", b, b+bucket_size-1)
  count[label]++
}
END {
  for (l in count) print l, count[l]
}' scores.txt | sort -t- -k1,1n

# ── Format bytes as human-readable ───────────────────────
awk 'function human(b,   s,u) {
  u[1]="B"; u[2]="KB"; u[3]="MB"; u[4]="GB"; u[5]="TB"
  for (s=1; b>=1024 && s<5; s++) b /= 1024
  return sprintf("%.1f%s", b, u[s])
}
{ print $1, human($2) }' transfer.log

# ── Format duration (seconds → human) ────────────────────
awk 'function duration(s,   d,h,m) {
  d = int(s/86400); s -= d*86400
  h = int(s/3600);  s -= h*3600
  m = int(s/60);    s -= m*60
  if (d > 0) return sprintf("%dd %dh %dm", d, h, m)
  if (h > 0) return sprintf("%dh %dm %ds", h, m, s)
  if (m > 0) return sprintf("%dm %ds", m, s)
  return sprintf("%ds", s)
}
{ print $1, duration($2) }' uptimes.txt

# ── Format with thousand separators (gawk) ───────────────
gawk 'function commas(n,   s,i,r) {
  s = sprintf("%d", n)
  r = ""
  for (i=length(s); i>0; i--) {
    if ((length(s)-i+1)%3==0 && i!=1) r = "," substr(s,i,1) r
    else r = substr(s,i,1) r
  }
  return r
}
{ printf "%-20s %s requests\n", $1, commas($2) }' stats.txt

# ── Percentage with bar chart ─────────────────────────────
awk '{ data[$1]+=$2; total+=$2 }
END {
  for (k in data) {
    pct = data[k]/total*100
    bar = sprintf("%-20s", "")
    for (i=0; i regions.txt | sort -k2 -rn