Hartigan/Computer/AWK

Hartigan/Computer/AWK
EXAMPLES # is the comment character for awk. 'field' means 'column'


# Print first two fields in opposite order:

  awk '{ print $2, $1 }' file
# Print lines longer than 72 characters:

  awk 'length > 72' file
# Print length of string in 2nd column

  awk '{print length($2)}' file
# Add up first column, print sum and average:

       { s  += $1 }

  END  { print "sum is", s, " average is", s/NR }
# Print fields in reverse order:

  awk '{ for (i = NF; i > 0; --i) print $i }' file
# Print the last line

      {line = $0}

  END {print line}
# Print the total number of lines that contain the word Pat

  /Pat/ {nlines = nlines   1}

  END {print nlines}
# Print all lines between start/stop pairs:

  awk '/start/, /stop/' file
# Print all lines whose first field is different from previous one:

  awk '$1 != prev { print; prev = $1 }' file
# Print column 3 if column 1 > column 2:

  awk '$1 > $2 {print $3}' file
# Print line if column 3 > column 2:

  awk '$3 > $2' file
# Count number of lines where col 3 > col 1

  awk '$3 > $1 {print i   "1"; i  }' file
# Print sequence number and then column 1 of file:

  awk '{print NR, $1}' file
# Print every line after erasing the 2nd field

  awk '{$2 = ""; print}' file
# Print hi 28 times

  yes | head -28 | awk '{ print "hi" }'
# Print hi.0010 to hi.0099 (NOTE IRAF USERS!)

  yes | head -90 | awk '{printf("hi00%2.0f n", NR 9)}'
# Replace every field by its absolute value

  { for (i = 1; i < = NF; i=i 1) if ($i < 0) $i = -$i print}

# If you have another character that delimits fields, use the -F option
# For example, to print out the phone number for Jones in the following file,
# 000902|Beavis|Theodore|333-242-2222|149092
# 000901|Jones|Bill|532-382-0342|234023
# ...
# type
  awk -F"|" '$2=="Jones"{print $4}' filename



# Some looping for printouts
  BEGIN{
        for (i=875;i>833;i--){

                printf "lprm -Plw %dn", i

        } exit

       }
 Formatted printouts are of the form printf( "formatn", value1, value2, ... valueN)

                e.g. printf("howdy %-8s What it is bro. %.2fn", $1, $2*$3)

        %s = string

        %-8s = 8 character string left justified

        %.2f = number with 2 places after .

        %6.2f = field 6 chars with 2 chars after .

        n is newline

        t is a tab
# Print frequency histogram of column of numbers

$2 < = 0.1 {na=na 1}
($2 > 0.1) && ($2 < = 0.2) {nb = nb 1}
($2 > 0.2) && ($2 < = 0.3) {nc = nc 1}
($2 > 0.3) && ($2 < = 0.4) {nd = nd 1}
($2 > 0.4) && ($2 < = 0.5) {ne = ne 1}
($2 > 0.5) && ($2 < = 0.6) {nf = nf 1}
($2 > 0.6) && ($2 < = 0.7) {ng = ng 1}
($2 > 0.7) && ($2 < = 0.8) {nh = nh 1}
($2 > 0.8) && ($2 < = 0.9) {ni = ni 1}
($2 > 0.9) {nj = nj 1}

END {print na, nb, nc, nd, ne, nf, ng, nh, ni, nj, NR}

# Find maximum and minimum values present in column 1 NR == 1 {m=$1 ; p=$1} $1 >= m {m = $1} $1 < = p {p = $1} END { print "Max = " m, " Min = " p } # Example of defining variables, multiple commands on one line NR == 1 {prev=$4; preva = $1; prevb = $2; n=0; sum=0} $4 != prev {print preva, prevb, prev, sum/n; n=0; sum=0; prev = $4; preva = $1; prevb = $2} $4 == prev {n ; sum=sum $5/$6} END {print preva, prevb, prev, sum/n} # Example of using substrings # substr($2,9,7) picks out characters 9 thru 15 of column 2 {print "imarith", substr($2,1,7) " - " $3, "out."substr($2,5,3)} {print "imarith", substr($2,9,7) " - " $3, "out."substr($2,13,3)} {print "imarith", substr($2,17,7) " - " $3, "out."substr($2,21,3)} {print "imarith", substr($2,25,7) " - " $3, "out."substr($2,29,3)}

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