How to use awk sort by column 3

How about just sort.

sort -t, -nk3 user.csv 

where

• -t, - defines your delimiter as ,.

• -n - gives you numerical sort. Added since you added it in your attempt. If your user field is text only then you dont need it.

• -k3 - defines the field (key). user is the third field.

1. Use awk to put the user ID in front.
2. Sort

3. Use sed to remove the duplicate user ID, assuming user IDs do not contain any spaces.

   awk -F, '{ print $3, $0 }' user.csv | sort | sed 's/^.* //' 

Seeing as that the original question was on how to use awk and every single one of the first 7 answers use sort instead, and that this is the top hit on Google, here is how to use awk.

Sample net.csv file with headers:

ip,hostname,user,group,encryption,aduser,adattr 192.168.0.1,gw,router,router,-,-,- 192.168.0.2,server,admin,admin,-,-,- 192.168.0.3,ws-03,user,user,-,-,- 192.168.0.4,ws-04,user,user,-,-,- 

And sort.awk:

#!/usr/bin/env -S awk -f # # original source: # https://stackoverflow.com/a/65768883/586229 # # Usage: # awk -f sort.awk [-F<field separator>] [-v h=HAS_HEADER] [-v f=COLUMN_TO_SORT_BY] INPUT_FILE # Examples: # awk -f sort.awk -F, -v h=1 -v f=1 input.csv > output.csv # cat input.txt | awk -f sort.awk | tee -a output.txt # for each line { if (h && NR == 0) { print $0 } else { a[NR-h]=$0 "" s[NR-h]=$f "" } } END { isort(s, a, NR-h); for (i = 1; i <= NR-h; i++) { print a[i] } } # insertion sort of A[1..n] function isort(S, A, n, i, j) { for (i = 2; i <= n; i++) { hs = S[j=i] ha = A[j=i] while (S[j-1] > hs) { j--; S[j+1] = S[j] A[j+1] = A[j] } S[j] = hs A[j] = ha } } 

To use it:
See header in the script.

Update: see my other answer for 100x speedup doing Quicksort instead of Insertion sort.

You can choose a delimiter, in this case I chose a colon and printed the column number one, sorting by alphabetical order:

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

awk -F, '{ print $3, $0 }' user.csv | sort -nk2 

and for reverse order

awk -F, '{ print $3, $0 }' user.csv | sort -nrk2 

try this -

awk '{print $0|"sort -t',' -nk3 "}' user.csv 

OR

sort -t',' -nk3 user.csv 

awk -F "," '{print $0}' user.csv | sort -nk3 -t ',' 

This should work

To exclude the first line (header) from sorting, I split it out into two buffers.

df | awk 'BEGIN{header=""; $body=""} { if(NR==1){header=$0}else{body=body"\n"$0}} END{print header; print body|"sort -nk3"}' 

With GNU awk:

awk -F ',' '{ a[$3]=$0 } END{ PROCINFO["sorted_in"]="@ind_str_asc"; for(i in a) print a[i] }' file 

See 8.1.6 Using Predefined Array Scanning Orders with gawk for more sorting algorithms.

Here is another actual awk sort script. This script is slightly longer, but 100x faster.

#!/usr/bin/env -S awk -f # Awk Quicksort # Usage: # awk -f sort.awk [-F<field separator>] [-v header=1] [-v field=N] [-v reverse=1] [-v numeric=1] INPUT_FILE # Examples: # awk -f sort.awk -F, -v header=1 -v field=1 input.csv > sorted.csv # awk -f sort.awk -F, -v header=1 -v field=2 -v reverse=1 -v numeric=1 input.csv > sorted.csv # cat input.txt | awk -f sort.awk -v field=3 | tee output.txt BEGIN { # Initialize variables if not set header = (header == "") ? 0 : header # Whether input has a header row field = (field == "") ? 1 : field # Column to sort by reverse = (reverse == "") ? 0 : reverse # Whether to sort in reverse order numeric = (numeric == "") ? 0 : numeric # Whether to use numeric sorting } # Store header separately if present NR == 1 && header { header_line = $0 next } # Store each line and its key for sorting { # Store the full line lines[NR - header] = $0 # Extract the sort key if (field <= NF) { keys[NR - header] = $field } else { # If field number is larger than available fields, use empty string keys[NR - header] = "" } } END { # Print header if present if (header) { print header_line } # Sort and print the data n = length(lines) quicksort(keys, lines, 1, n) # Print sorted results for (i = 1; i <= n; i++) { idx = reverse ? n - i + 1 : i print lines[idx] } } # Quicksort implementation function quicksort(keys, lines, left, right) { if (left >= right) return # Choose pivot (middle element) pivot_idx = int((left + right) / 2) pivot = keys[pivot_idx] # Partition i = left j = right while (i <= j) { while (compare(keys[i], pivot) < 0) i++ while (compare(keys[j], pivot) > 0) j-- if (i <= j) { # Swap elements temp_key = keys[i] temp_line = lines[i] keys[i] = keys[j] lines[i] = lines[j] keys[j] = temp_key lines[j] = temp_line i++ j-- } } # Recursive calls if (left < j) quicksort(keys, lines, left, j) if (i < right) quicksort(keys, lines, i, right) } # Comparison function that handles both numeric and string comparisons function compare(a, b) { if (numeric) { return (a + 0) - (b + 0) # Force numeric comparison } return a < b ? -1 : (a > b ? 1 : 0) } 

To use it:
For usage examples, see the header in the script. Or save it to a file called sort.awk, and then chmod +x sort.awk, then you can call it like any other program, with ./sort.awk ...

I'm running Linux (Ubuntu) with mawk:

tmp$ awk -W version mawk 1.3.4 20200120 Copyright 2008-2019,2020, Thomas E. Dickey Copyright 1991-1996,2014, Michael D. Brennan random-funcs: srandom/random regex-funcs: internal compiled limits: sprintf buffer 8192 maximum-integer 2147483647 

mawk (and gawk) has an option to redirect the output of print to a command. From man awk chapter 9. Input and output:

The output of print and printf can be redirected to a file or command by appending > file, >> file or | command to the end of the print statement. Redirection opens file or command only once, subsequent redirections append to the already open stream.

Below you'll find a simplied example how | can be used to pass the wanted records to an external program that makes the hard work. This also nicely encapsulates everything in a single awk file and reduces the command line clutter:

tmp$ cat input.csv alpha,num D,4 B,2 A,1 E,5 F,10 C,3 

tmp$ cat sort.awk # print header line /^alpha,num/ { print } # all other lines are data lines that should be sorted !/^alpha,num/ { print | "sort --field-separator=, --key=2 --numeric-sort" } 

tmp$ awk -f sort.awk input.csv alpha,num A,1 B,2 C,3 D,4 E,5 F,10 

See man sort for the details of the sort options:

-t, --field-separator=SEP use SEP instead of non-blank to blank transition -k, --key=KEYDEF sort via a key; KEYDEF gives location and type -n, --numeric-sort compare according to string numerical value