How to use arrays in ksh?

  Array, as in any programming language, is a collection of elements. These elements need not be of the same type. One important difference here is shells support only one-dimensional arrays.

1. Creating an array:
   Creating an array is pretty simple.

$ typeset -a arr
$ arr[0]=25
$ arr[1]=18
$ arr[2]="hello"

 Using the typeset command, we let the shell know that we are intending to use the variable arr to store a list of elements. The -a indicates arr as an indexed array. Then the elements are assigned one by one using their index positions. Array indexing always starts from 0.

Perl : Find files using File::Find

How to find the list of files in Perl  like the UNIX find command? The answer is File::Find CPAN module. Let us see in this article how to use the File::Find module.

File::Find:
   File::Find module contains 2 modules: find and finddepth. Both are used to find the files, the difference being the order in which the files and directories are parsed. find has all the options like the Unix find command.

sed - 20 examples to remove / delete characters from a file

In this article of sed series, we will see the examples of how to remove or delete characters from a file. The syntax of sed command replacement is:

$ sed 's/find/replace/' file

 This sed command finds the pattern and replaces with another pattern. When the replace is left empty, the pattern/element found gets deleted.

Let us consider a sample file as below:

$ cat file
Linux
Solaris
Ubuntu
Fedora
RedHat

How to use SUID for shell scripts in Linux?

Question : How to write a shell script which will read the required passwords/connect strings from a config file? Other users should be able to execute the scripts, however they should not be able to read the config file.

Say, I have a config file, myconfig.txt, which contains credentials for an oracle connection:

$ cat myconfig.txt
SQLUSR="scott"
SQLPWD="pwd123"

Python - How to write a list to a file?

How to write an entire list of elements into a file? Let us see in this article how to write a list l1 to a file 'f1.txt':

1. Using write method:

#!/usr/bin/python

l1=['hi','hello','welcome']

f=open('f1.txt','w')
for ele in l1:
    f.write(ele+'\n')

f.close()

 The list is iterated, and during every iteration, the write method writes a line to a file along with the newline character.