shell pipes – nixCraft

Shell Script To Translate All Characters In a File To Lowercase

in File-management last updated September 16, 2008

A UNIX shell script to translate all the characters to lower case in a given text file.

Shell Script that outputs the number of users with entries in the /etc/passwd file

in File-management last updated April 9, 2008

#!/bin/bash
# Shell Script that outputs the number of users with entries in the
# Unix or Linux /etc/passwd file
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
PASSWD=/etc/passwd

# easy method with wc
OUT=$(wc -l $PASSWD)

# More accurate method to find out
# If user account suspended using # character then second method 
# is more accurate and recommend
OUT1=$(grep -Ev "^#" $PASSWD | wc -l)

echo "$OUT [$OUT1]"
# You can filter result with awk
echo $OUT | awk '{ print $1 }'

#!/bin/bash

# Shell Script that outputs the number of users with entries in the

# Unix or Linux /etc/passwd file

# -------------------------------------------------------------------------

# This script is licensed under GNU GPL version 2.0 or above

# -------------------------------------------------------------------------

# This script is part of nixCraft shell script collection (NSSC)

# Visit http://bash.cyberciti.biz/ for more information.

# -------------------------------------------------------------------------

PASSWD=/etc/passwd

# easy method with wc

OUT=$(wc -l $PASSWD)

# More accurate method to find out

# If user account suspended using # character then second method

# is more accurate and recommend

OUT1=$(grep -Ev "^#" $PASSWD | wc -l)

echo "$OUT [$OUT1]"

# You can filter result with awk

echo $OUT | awk '{ print $1 }'

Shell script to read 5 digit number and calculate the sum of digit

in Shell Math last updated April 4, 2008

#!/bin/bash
# Shell script to read 5 digit number and calculate the sum of digit
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------

echo -n "Enter numnber : "
read n

# find out length of string using wc -c command
len=$(echo $n | wc -c)

# remove \n i.e. new line character
len=$(( $len - 1 ))

# use loop to go throug all digit one by one and calculate sum of digit on fly
for (( i=1; i <= $len; i++ ))
do
   sum=$(( $sum + $(echo $n | cut -c $i) ))
done
echo "Sum of $n is $sum"

#!/bin/bash

# Shell script to read 5 digit number and calculate the sum of digit

# -------------------------------------------------------------------------

# This script is licensed under GNU GPL version 2.0 or above

# -------------------------------------------------------------------------

# This script is part of nixCraft shell script collection (NSSC)

# Visit http://bash.cyberciti.biz/ for more information.

# -------------------------------------------------------------------------

echo -n "Enter numnber : "

read n

# find out length of string using wc -c command

len=$(echo $n | wc -c)

# remove \n i.e. new line character

len=$(( $len - 1 ))

# use loop to go throug all digit one by one and calculate sum of digit on fly

for (( i=1; i <= $len; i++ ))

sum=$(( $sum + $(echo $n | cut -c $i) ))

done

echo "Sum of $n is $sum"

Shell Script to display current date, calendar, and the number of user logged

in Academic last updated April 3, 2008

This script use the concept of command substitution. It allows allows the output of a command to replace the command name. There are two forms:

$(command)

command

Bash shell performs the expansion by executing command and replacing the command substitution with the standard output of the command, with any trailing newlines deleted. Embedded newlines are not deleted, but they may be removed during word splitting.

For example you can execute date command to display todays date and then set a variable called NOW:
NOW=$(date)
or
NOW=date
To display back variable value simply run echo command:
echo $NOW

Sample Shell Script

#!/bin/bash
# Shell script to display current date, calendar, and the number of
# user logged.
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# ----------------------------------------------------------------------
echo "Today is $(date)"
echo ""

echo "Calendar :"
cal

echo "Number of users currently logged : $(who | wc -l)"

#!/bin/bash

# Shell script to display current date, calendar, and the number of

# user logged.

# -------------------------------------------------------------------------

# This script is licensed under GNU GPL version 2.0 or above

# -------------------------------------------------------------------------

# This script is part of nixCraft shell script collection (NSSC)

# Visit http://bash.cyberciti.biz/ for more information.

# ----------------------------------------------------------------------

echo "Today is $(date)"

echo ""

echo "Calendar :"

cal

echo "Number of users currently logged : $(who | wc -l)"