Sstrhsrtj

I have written a bash program that scans through /etc/passwd and prints out all of the usernames that are in the directory however i need the program to only print out usernames that are between 5 and 10 characters long.
I need to change it.

#!/bin/bash



MAXLENGTH=$(cut -d: -f1 < /etc/passwd | wc -L)

MINLENGTH=$MAXLENGTH

SMALLESTNAME=""



for NAME in $(cut -d: -f1 < /etc/passwd)

do

if [ ${#NAME} -eq $MAXLENGTH ]

then

        echo "The Longest UserName In The System 

Is:" $NAME

        echo " Its Length Is" $MAXLENGTH

elif [ ${#NAME} -lt $MINLENGTH ]

then

        MINLENGTH=${#NAME}

        SMALLESTNAME=$NAME

fi



done



 echo

 echo "The Smallest UserName In The System Is:" 

 $SMALLESTNAME

 echo "Its Length is:" $MINLENGTH

getent passwd | awk -F : 'length($1) >= 5 && length($1) <= 10 { print $1 }'

This will print the usernames that are between 5 and 10 characters long (inclusively).

For the shortest and longest names:

getent passwd |

awk -F : 's == "" || length($1) < length(s) { s = $1 }

          l == "" || length($1) > length(l) { l = $1 }

          END { printf("shortest: %s (%d chars)n", s, length(s))

                printf("longest:  %s (%d chars)n", l, length(l)) }'

Doing both things with a single pass over the password database (as a complete bash script, although /bin/sh should have been far more than enough since this script does not use anything bash specific, any shell would be able to run it):

#!/bin/bash

getent passwd |

awk -F : 'length($1) >= 5 && length($1) <= 10 { print $1 }

          s == "" || length($1) < length(s)   { s = $1   }

          l == "" || length($1) > length(l)   { l = $1   }

          END { printf("shortest: %s (%d chars)n", s, length(s))

                printf("longest:  %s (%d chars)n", l, length(l)) }'

Impractical but somewhat mesmerizing: bash extended file patterns:

shopt -s extglob



getent passwd | 

  cut -d: -f1 | 

  while IFS= read -r name; do 

    [[ $name == ?????@(|?|??|???|????|?????) ]] && echo "$name"

  done

Here's your homework solution:

#!/bin/bash

for NAME in $(cut -d: -f1 < /etc/passwd)

do

        if [[ ${#NAME} -gt 10 || ${#NAME} -lt 5 ]]

        then

                continue

        else

                echo "Username in the system is: $NAME"

                echo "Its length Is ${#NAME}"

        fi

done

You're welcome.

For a little more variety, cut and grep:

getent passwd | cut -d: -f1 | grep -Ex '.{5,10}'

This retrieves the passwd entries, cuts out the first field (username), then asks grep for an Extended regular expression match that spans the entire line (-x) where there are between 5 and 10 of any character (.).