search and edit in the same file using awk

Shell Programming and Scripting
1

Hi,
I am having a user.txt contains the name of users and passwd.txt file contains as passwd.txt

$cat usr.txt
root
bin
daemon
cap

$cat passwd.txt
root:x:0:0:root:/root:/usr/bin/ksh
bin:x:1:1:bin:/bin:/sbin/csh
daemon:x:2:2:daemon:/sbin:/usr/bin/ksh
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/usr/bin/ksh

I want to change the 7th field of passwd.txt to /bin/sh when usr.txt users match with the 1st field of passwd.txt .
I have done so far ....

#!/bin/sh
file=/etc/log/user.txt
passwd_file=/var/log/passwd.txt
cat $file |while read i
do 
awk -F: -v i="$i" '/$1 ~ i/{gusb("/usr/bin/ksh", "/bin/sh", $0);print > FILENAME} ' passwd_file 
done

$cat passwd.txt
root:x:0:0:root:/root:/bin/sh
bin:x:1:1:bin:/bin:/sbin/csh
daemon:x:2:2:daemon:/sbin:/bin/sh
adm:x:3:4:adm:/var/adm:/sbin/nologin
lp:x:4:7:lp:/var/spool/lpd:/usr/bin/ksh
2 
nawk 'FNR==NR{u[$1];next}$1 in u {$7="/bin/sh"}1' FS=: OFS=: usr.txt passwd.txt

or if you want to edit 'in-place':

nawk 'FNR==NR{u[$1];next}$1 in u {$7="/bin/sh"}{l[FNR]=$0}END {close(FILENAME);for(;++i in l;) print l>FILENAME}' FS=: OFS=: usr.txt passwd.txt
3

I think the first awk should be fine enough.

4

Thanks vgersh99 for the code

nawk 'FNR==NR{u[$1];next}$1 in u {$7="/bin/sh"}{l[FNR]=$0}END {close(FILENAME);for(;++i in l;) print l>FILENAME}' FS=: OFS=: usr.txt passwd.txt

But in my OS nawk is not supporting But if i go for awk this command work fine for me in SHELL But when i keep this thing in a shell script it won't works. Getting error unable to read passwd.txt file.

Thanks
Manabhanjan

5

Well.... my crystal ball says that your script cannot find or read the passwd.txt file.
I'd suggest to start debugging the script.
Good luck.