Get the longest logon time of a given user using awk - bash

Question

My task is to write a bash script, using awk, to find the longest logon of a given user ("still logged in" does not count), and print the month day IP logon time in minutes.
Sample input: ./scriptname.sh username1
Content of last username1:
username1 pts/ IP Apr 2 .. .. .. .. (00.03)
username1 pts/ IP Apr 3 .. .. .. .. (00.13)
username1 pts/ IP Apr 5 .. .. .. .. (12.00)
username1 pts/ IP Apr 9 .. .. .. .. (12.11)
Sample output:
Apr 9 IP 731
(note: 12 hours and 11 minutes is in total 731 minutes)
I have written this script, but a bunch of errors pop up, and I am really confused:
#!/bin/bash
usr=$1
last $usr | grep -v "still logged in" | awk 'BEGIN {max=-1;}
{
h=substr($10,2,2);
min=substr($10,5,2) + h/60;
}
(max < min){
max = min;
}
END{
maxh=max/60;
maxmin=max-maxh;
($maxh == 0 && $maxmin >=10){
last $usr | grep "00:$maxmin" | awk '{print $5," ",$6," ", $3," ",$maxmin}'
exit 1
}
($maxh == 0 $$ $maxmin < 10){
last $usr | grep "00:0$maxmin" | awk '{print $5," ",$6," ",$3," ",$maxmin}'
exit 1
}
($maxh < 10 && $maxmin == 0){
last $usr | grep "0$maxh:00" | awk '{print $5," ",$6," ",$3," ",$maxmin}'
exit 1
}
($maxh < 10 && $maxmin < 10){
last $usr | grep "0$maxh:0$maxmin" | awk '{print $5," ",$6," ",$3," ",$maxmin}'
exit 1
}
($maxh >= 10 && $maxmin < 10){
last $usr | grep "$maxh:0$maxmin" | awk '{print $5," ",$6," ",$3," ",$maxmin}'
exit 1
}
($maxh >=10 && $maxmin >= 10){
last $usr | grep "$maxh:$maxmin" | awk '{print $5," ",$6," ",$3," ",$maxmin}'
exit 1
}
}'
So a bit of explaining of how I imagined this would work:
After the initialization, I want to find the (hh:mm) column of the last $usr command, save the h and min of every line, find the biggest number (in minutes, meaning it is the longest logon time).
After I found the longest logon time (in minutes, stored in the variable max), I then have to reformat the only minutes format to hh:mm to be able to use a grep, use the last command again, but now only searching for the line(s) that contain the max logon time, and print all of the needed information in the month day IP logon time in minutes format, using another awk.
Errors I get when running this code: A bunch of syntax errors when I try using grep and awk inside the original awk.

Answer 1

awk is not shell. You can't directly call tools like last, grep and awk from awk any more than you could call them directly from a C program.
Using any awk in any shell on every Unix box and assuming if multiple rows have the max time you'd want all of them printed and that if no timestamped rows are found you want something like No matching records printed (easy tweak if not, just tell us your requirements for those cases and include them in the example in your question):
last username1 |
awk '
/still logged in/ {
next
}
{
split($NF,t,/[().]/)
cur = (t[2] * 60) + t[3]
}
cur >= max {
out = ( cur > max ? "" : out ORS ) $4 OFS $5 OFS $3 OFS cur
max = cur
}
END {
print (out ? out : "No matching records")
}
'
Apr 9 IP 731

Answer 2

If gnu-awk is available, you might use a pattern with 2 capture groups for the numbers in the last field. In the END block print the format that you want.
If in this example, file contains the example content, and the last column contains the logon:
awk '
match ($(NF), /\(([0-9]+)\.([0-9]+)\)/, a) {
hm = (a[1] * 60) + a[2]
if(hm > max) {max = hm; line = $0;}
}
END {
n = split(line,a,/[[:space:]]+/)
print a[3], a[4], a[5], max
}
' file
Output
IP Apr 9 731

Answer 3

Testing last command in my machine:
Using Red Hat Linux 7.8
Got the following output:
user0022 pts/1 10.164.240.158 Sat Apr 25 19:32 - 19:47 (00:14)
user0022 pts/1 10.164.243.80 Sat Apr 18 22:31 - 23:31 (1+01:00)
user0022 pts/1 10.164.243.164 Sat Apr 18 19:21 - 22:05 (02:43)
user0011 pts/0 10.70.187.1 Thu Nov 21 15:26 - 18:37 (03:10)
user0011 pts/0 10.70.187.1 Thu Nov 7 16:21 - 16:59 (00:38)
astukals pts/0 10.70.187.1 Mon Oct 7 19:10 - 19:13 (00:03)
reboot system boot 3.10.0-957.10.1. Mon Oct 7 22:09 - 14:30 (156+17:21)
astukals pts/0 10.70.187.1 Mon Oct 7 18:56 - 19:08 (00:12)
reboot system boot 3.10.0-957.10.1. Mon Oct 7 21:53 - 19:08 (-2:-44)
IT pts/0 10.70.187.1 Mon Oct 7 18:50 - 18:53 (00:03)
IT tty1 Mon Oct 7 18:48 - 18:49 (00:00)
user0022 pts/1 30.30.30.168 Thu Apr 16 09:43 - 14:54 (05:11)
user0022 pts/1 30.30.30.59 Wed Apr 15 11:48 - 04:59 (17:11)
user0022 pts/1 30.30.30.44 Tue Apr 14 19:03 - 04:14 (09:11)
Found time format is DD+HH:MM appears only when DD is not zero.
Found there are additional technical users: IT, system, reboot need to filtered.
Suggesting solution:
last | awk 'BEGIN {FS="[ ()+:]*"}
/reboot|system|still/{next}
{ print $5 OFS $6 OFS $3 OFS $(NF-1) + ($(NF-2) * 60) + ($(NF-3) * 60 * 24)}
' |sort -nk 4| head -1
Result:
Apr 15 30.30.30.59 85991