Using AWK

//print the first column

awk -F":" ' { print $1 } ' /etc/passwd  

// print 1st column and last column

awk -F":" ' { print $1, $NF} ' /etc/passwd 

//print 1st column of 1st ten records

awk -F":" ' NR==1,NR==10 { print $1 } ' /etc/passwd

//print 1st column length of 1st ten records 

awk -F":" ' NR==1,NR==10 { print length($1) } ' /etc/passwd 

// using printf to format output

awk -F":" ' NR==1,NR==10 { printf "%-8s %3d\n" , $1,$3 } ' /etc/passwd 

// add header and footer for output

awk -F":" '

BEGIN { printf "%-8s %-3s\n" , "User", "UID" }

NR==1,NR==10 { printf "%-8s %3d\n" , $1,$3 } 

END { print "============== END ============="} ' /etc/passwd

// add output filed separator between columns

awk -F":" ' { OFS="|";print $1, $NF } ' /etc/passwd

// condition

awk -F":" ' /^root/ { print $1, $NF } ' /etc/passwd

awk -F":" ' { if($1 ~ /root/) { print $1, $NF } }' /etc/passwd

Written on March 27, 2017