UNIX for Dummies Questions & Answers

wow, back again

I am trying to write a program that has many functions, however one of the functions will count the total number of users in the database.


I want to just use wc -l passwd (i've made a copy of passwd to play with, no worries lol)

but I am worried that if any of the accounts contained enough info to be longer than one line of text, it would mess up. Am I correct in my assumption, or does unix read an extended line still as one line?

should I use the 'cut' command to just read the first field? If so, how?

I dunno how different other versions of unix/linux are, but my passwd file is done like this:
root:x:0:0:root:root:/bin/bash


also, how would like to save the number of users as a variable, but not include the name of the file ('wc -l passwd' gives me a reply of # passwd, and i dont want the word passwd to show up)

thanks in advance!

The passwd file only contains one user per line. If a users details appears to wrap to the next line, it's to do with your terminal size, not the file itself.

Use

Code:

VAR=$(wc -l < passwd)

to get rid of the filename.

HTH

god bless u for answering both my questions

You're welcome. But note that not all users in the passwd file are really "people". i.e. on my Mac there are 65 entries in the passwd file, and there's only me and root (also me) in the vicinity

Special "users" like daemon, nobody, lpr, etc. are used by the system for various functions.

If you have any convention by which user ID's are assigned, you may want to count only those that match.

i.e. assuming that "real" user IDs start from 1000:

Code:

awk -F: '$3 >= 1000 { C++ } END { print C+0 }' /etc/passwd

(or shorter, with wc)

Code:

awk -F: '$3 >= 1000' passwd | wc -l

Or you could count the users for whom a passwd has been set, e.g.

Code:

awk -F: 'length($2)>1' /etc/shadow | wc -l

depending on the security method used..
or

Code:

awk -F: 'length($2)>1{t++}END{print t+0}' /etc/shadow

Which presumably is a bit safer...