Question

As a part of my homework exercise, i am finding it difficult to execute the following two commands. Can you please rectify the error in it. Thanks in advance

Write a program, that will take a file which has a set of directories, and will
look into these directories and their sub directories for any files named core.*
and *.o and will print a report of all such files found. (you can use find)

For the above program i attempted to do like this.

cat prog1 | xargs find /$0 -name 'core.*' or '*.o'

But I am getting the following error. (prog1 is a file containing list of directories)

find: paths must precede expression: perl
Usage: find [-H] [-L] [-P] [-Olevel] [-D help|tree|search|stat|rates|opt|exec] [path...] [expression]

The next question is:

Write a script that will go through the /etc/passwd file, and from this print a list of users in the system, their home directory and the shell that they are using

For which I tried the following:

awk '{print "USER \t\t HOME \t\t BASH \n split($0,a,":")}
     {print $a[1] \t\t $a[6] \t\t   $a[7]}' /etc/passwd

I tried googling and seeing the man entries but I don’t understand the error. Also can you provide some useful links to shell scripting for beginners?

Answer 1

Write a program, that will take a file which has a set of directories, and will
look into these directories and their sub directories for any files named core.*
and *.o and will print a report of all such files found.  (you can use find) 

I suggest following oneliner:

find `paste -s -d' ' directories.list` -type f -name 'core.*' -or -name '*.o'

Where directories.list contains directories names, one by line.

Write a script that will go through the /etc/passwd file, and from this print a
list of users in the system, their home directory and the shell that they are
using

Try this:

awk -F: 'BEGIN{print "USER\t\tHOME\t\tSHELL"}{printf("%s\t\t%s\t\t%s\n", $1, $6, $7)}' /etc/passwd