awk

A practical reference for AWK, the classic Unix pattern scanning and text processing language, with concise examples for filtering, transforming, and analyzing structured text

Print hello world

awk 'BEGIN { print "hello, world" }'

Print hello world with multi-line

awk '
    BEGIN {
        print "hello, world"
    }
'

Print all matches of a string (alias)

awk '/alias/' ~/.bashrc

Remove lines with string alias

awk '!/alias/' ~/.bashrc

Print field start with string (e.g Linux)

awk '$1 ~ /^alias/' ~/.bashrc

Remove last column

awk 'NF{NF-=1};1' ~/.bashrc

Break combine column data into rows

awk '{split($2,a,",");for(i in a)print $1"\t"a[i]}' ~/.bashrc

Reverse column order

awk '{print $2, $1}' ~/.bashrc

Split and do for loop

awk '{split($2, a,",");for (i in a) print $1"\t"a[i]}' ~/.bashrc

Print all lines before nth occurrence of a string (e.g stop print lines when ‘alias’ appears 7 times)

awk -v N=7 '{print}/alias/&& --N<=0 {exit}' ~/.bashrc

Give number to every row

awk '{printf("%s\t%s\n",NR,$0)}' ~/.bashrc

Print filename and last line of all files in directory

ls|xargs -n1 -I file awk '{s=$0};END{print FILENAME,s}' ~/.bashrc

Add string to the beginning of a column (e.g add testing to column $3)

awk 'BEGIN{OFS="\t"}$2"testing"$2' ~/.bashrc

Print line number and number of characters on each line

awk '{print NR,length($0);}' ~/.bashrc

Show uptime in minutes

awk '{print int($1/3600)"h", int(($1%3600)/60)"m"}' /proc/uptime

Display system load averages from /proc/loadavg

awk '{print $1, $2, $3}' /proc/loadavg

Print duplicate lines using awk

awk '++seen[$0] == 2 { print }'

Print entire file contents with awk

awk '{ print $0 }' /proc/cmdline

Print first field from /proc/cmdline using awk

awk '{ print $1 }' /proc/cmdline

Print eighth field from /proc/cmdline using awk

awk '{ print $8 }' /proc/cmdline

Print lines containing the exact word root

awk '/\<root\>/' /etc/passwd

Print every line that includes ro from /etc/passwd

awk '/ro/ { print $0 }' /etc/passwd

Print every line that is shorter then 80 characters from /etc/passwd

awk 'length($0) < 80' /etc/passwd

Print every line that is longer than 80 characters

awk 'length($0) > 80' `/etc/passwd`

Print the length of the longest input line from /etc/passwd

awk '{ if (length($0) > max) max = length($0) }
 END { print max }' /etc/passwd

Print the length of the longest line in /etc/passwd

cat /etc/passwd| awk '{ if (x < length($0)) x = length($0) }
               END { print "maximum line length is " x }'

Print every line that has at least one field

This is an easy way to delete blank lines from a file (or rather, to create a new file similar to the old file but from which the blank lines have been removed)

awk 'NF > 0' data

Print seven random numbers from 0 to 100, inclusive

awk 'BEGIN { for (i = 1; i <= 7; i++)
             print int(101 * rand()) }'

Print the total number of bytes used by files

ls -l files | awk '{ x += $5 }
               END { print "total bytes: " x }'

Print the total number of kilobytes used by files

ls -l files | awk '{ x += $5 }
   END { print "total K-bytes:", x / 1024 }'

Print a sorted list of the login names of all users

awk -F: '{ print $1 }' /etc/passwd | sort

Count the lines in a file

awk 'END { print NR }' data

Print the even-numbered lines in the data file

awk 'NR % 2 == 0' /etc/passwd

Print the odd-numbered lines in the data file

awk 'NR % 2 == 1' /etc/passwd

Print each line that contains 10 in /etc/passwd

awk '/10/ { print }' /etc/passwd

Print each line that contains 1000 in /etc/passwd

awk '/1000/ { print }' /etc/passwd

Print all files that has been modified in Jan (january month)

ls -l | awk '$0 == "Jan" { print }'

Print lines containing the exact word 1000

awk '/\<1000\>/' /etc/passwd

Extract the Username Field from /etc/passwd Using awk

sed 1q /etc/passwd | awk '{ FS = ":" ; print $1 }'

Print all files and folders that has been created/modified in January month

awk field	Description
`$1`	file permissions
`$2`	number of hard links
`$3`	owner
`$4`	group
`$5`	file size (bytes)
`$6`	month (Jan, Feb, …)
`$7`	day
`$8`	time or year
`$9`	filename

```bash
ls -l | awk '$6 == "Jan" { print }'
```

Print entries between the bin and news users in /etc/passwd

awk '/^bin:/,/^news:/' /etc/passwd

Just print "Dont Panic

awk 'BEGIN { print "Don\47t Panic!" }'

The following one-liner prints a list of usernames from /etc/passwd

awk -F":" '{print $1 }' /etc/passwd

Mixing single and double quotes is difficult. You have to resort to shell quoting tricks, like this

awk 'BEGIN { print "Here is a single quote <'"'"'>" }'

The field separator can also be set in a BEGIN function block

awk 'BEGIN { FS=":" } {print $1 }' /etc/passwd

Every user whose shell is not /sbin/nologin can be printed by preceding the block with a pattern match:

awk 'BEGIN { FS=":" } ! /\/sbin\/nologin/ {print $1 }' /etc/passwd

Remove duplicate entries in a file without sorting

awk '!NF || !seen[$0]++' /etc/passwd
awk '!(NF && seen[$0]++)' /etc/passwd
awk '!/./ || !seen[$0]++' /etc/passwd
awk '!(NF && seen[$0]++)' /etc/passwd

Print entire line

awk '{print $0}' /some/file

Convert to uppercase and print line 2

awk 'NR==2 {print toupper($0)}' /etc/os-release

Convert to lowercase and print line 2

awk 'NR==2 {print tolower($0)}' /etc/os-release

Find all lines that begins on Example and delete one line below

awk '/^Example:/ { getline; next } 1' file.txt

Print current cpu usage for all cores

awk -F": " '/cpu MHz */ { print "Processor (or core) running speed is: " $2 }' /proc/cpuinfo

Get cpu running speed

awk '{ print "Processor running speed is:", $1/1000, "MHz" }' /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

Another way to get cpu running speed in mhz

awk '{ print "Processor running speed is:", $1/1000, "MHz" }' /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq

Get average processor speed

awk '{ sum += $1; n++ }
    END { printf "Average processor running speed is: %.2f MHz\n", sum/n/1000 }' \
    /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq

Print cpu base speed in GHz

awk -F'@ ' '
    /model name/ { base = $2; exit }
    END { print "Processor base speed is:", base }
    ' /proc/cpuinfo

Print cpu temperature by awk script

for f in /sys/class/hwmon/hwmon*/temp*_input; do
  base="${f%_input}"
  label_file="${base}_label"

  label=$(cat "$label_file" 2>/dev/null || echo "$(basename "$base")")
  awk -v label="$label" '{printf "%-12s %.1f°C\n", label ":", $1/1000}' "$f"
done

Print uptime in hours

awk '{ printf "%dh\n", int($1/3600) }' /proc/uptime

Print date and timesmpta

awk '{t=int($1);printf "%d days %02d:%02d:%02d\n",t/86400,(t%86400)/3600,(t%3600)/60,t%60}' /proc/uptime

Print uptime from uptime to timestamp

awk '{
  t = int($1)
  d = t / 86400
  t %= 86400
  h = t / 3600
  t %= 3600
  m = t / 60
  s = t % 60
  printf "%d days %02d:%02d:%02d\n", d, h, m, s
}' /proc/uptime

Print uptime from uptime to timestamp

awk '{printf "%d days %02d:%02d:%02d\n",
int($1/86400),
int($1%86400/3600),
int($1%3600/60),
int($1%60)}' /proc/uptime

Column subtraction

cat file| awk -F '\t' 'BEGIN {SUM=0}{SUM+=$3-$2}END{print SUM}'

Print duplicates side by side

awk '
{
    lines[$0] = lines[$0] ? lines[$0] RS NR ":" $0 : NR ":" $0
}
END {
    for (l in lines)
        if (split(lines[l], a, RS) > 1)
            print a[1] "\t|\t" a[2]
}
' $SOMEPATH/filename.md | column -ts $'\t'

A shorter way to print duplicates side by side

awk '
++seen[$0]==1 { first[$0]=$0 }
seen[$0]==2 { print first[$0] "\t|\t" $0 }
' filename.md | column -ts $'\t'

Generate fake mac addresses from bluetoothctl devices to hide our real mac addresses online

bluetoothctl devices | awk '
BEGIN { srand() }
{
    printf "Device %02X:%02X:%02X:%02X:%02X:%02X ",
        rand()*256, rand()*256, rand()*256,
        rand()*256, rand()*256, rand()*256
    for (i=3;i<=NF;i++) printf "%s%s", $i, (i<NF?" ":"")
    print ""
}'
Device 7C:47:EE:54:54:9C WH-1000XM5
Device C5:36:E2:64:07:9B Samsung S24 Ultra
Device 07:D4:CC:6C:78:1D [Samsung] Soundbar
Device 65:B4:9C:B5:A4:B2 Jabra Evolve 65
Device B2:31:10:74:CA:12 Moto G50
Device 17:CB:00:7B:74:72 WH-1000XM4
Device 76:84:29:BA:28:1C Galaxy Watch5 Pro (RMCF)

Above awk script shuffle the mac addresses so we get new ones everytime we run the awk script

Running above command again

bluetoothctl devices | awk '
BEGIN { srand() }
{
    printf "Device %02X:%02X:%02X:%02X:%02X:%02X ",
        rand()*256, rand()*256, rand()*256,
        rand()*256, rand()*256, rand()*256
    for (i=3;i<=NF;i++) printf "%s%s", $i, (i<NF?" ":"")
    print ""
}'
Device 13:6D:0A:A0:89:57 WH-1000XM5
Device BA:5C:77:89:5C:43 Samsung S24 Ultra
Device 7B:1B:91:C6:72:64 [Samsung] Soundbar
Device 7F:C8:02:25:79:60 Jabra Evolve 65
Device C3:D2:4D:42:B4:73 Moto G50
Device 4E:25:FC:33:2B:B2 WH-1000XM4
Device CA:28:C8:B4:D0:06 Galaxy Watch5 Pro (RMCF)

Setup markdowns easy

Example: We got commandehre | description here then it will add our syntax

cat input.txt | awk -F' *\\| *' '
{
printf "!!! Example \"%s\"\n\n    ```bash\n    gsettings %s\n    ```\n\n", $2, $1
}
'

If we got "Text1 | Text2 | It will add it to bash syntax with !!! Example

awk -F'|' '
{
    id=$1
    desc=$2
    gsub(/^[ \t]+|[ \t]+$/, "", id)
    gsub(/^[ \t]+|[ \t]+$/, "", desc)

    printf "!!! Example \"%s\"\n\n", desc
    printf "    ```bash\n"
    printf "    kcmshell6 %s\n", id
    printf "    ```\n\n"
}
' filename.txt

Resource(s)