Useful Unix Commands

1.Unix command to display column -3 info from file

Suppose the sample file (test4.txt) is as follows

col1|gcol2|col3|col4|col5

r1c1|gr1c2|r1c3|r1c4|r1c5

r2c1|gr2c2|r2c3|r2c4|r2c5

r3c1|gr3c2|r3c3|r3c4|r3c5

r4c1|gr4c2|r4c3|r4c4|r4c5

To display column-3 use following command

awk -F '|' '{print $3}' test4.txt

-F -> Field separator

$3 -> column 3

Or use cut command

cut -d'|' -f3 test4.txt

-d -> delimitor

-f3 -> column 3 values

2.Sed command to find and replace a character

Suppose file (test_1.txt) exists with below text and we want to replace pipe | with space

col1|col2|col3|col4|col5

r1c1|r1c2|r1c3|r1c4|r1c5

r2c1|r2c2|r2c3|r2c4|r2c5

r3c1|r3c2|r3c3|r3c4|r3c5

r4c1|r4c2|r4c3|r4c4|r4c5

sed command as follows

sed 's/\|/ /g' test_1.txt > t5.txt

Following is the command if we open the .txt file in vi editor

:%s/\|/ /g

3. Case Example in Unix

while getopts d:s:m: arg

do

case $arg in

dl)

date_list="$OPTARG"

;;

sl)

stage_list="$OPTARG"

;;

rm)

run_mode="$OPTARG"

;;

\?)

echo "Usage : $0 [-dl from_to_dates] [-sl from_to_stage] [-rm run_mode]"

echo "Ex: $0 -dl 01-jan-2001,01-dec-2001 -sl 1,2 -rm NORMAL"

exit 2

;;

esac

done

echo date_list $date_list

echo stage_list $stage_list

echo run_mode $run_mode

4. Unix IF ELSE Test

UNIX script to test the variable string is null or not

#! /usr/bin/ksh

run_mode="RERUN"

if [ "${run_mode}" = "" ]; then

echo With inif 

else

echo "${run_mode}"

fi

5. UNIX command to find files owned by user

find / -user rama 2>/dev/null | ls –ltr

6. Unix command to remove blank lines

sed '/^\s*$/d' 1.txt > 2.txt

7. IF ELSE Logic in shell script … search for a string in a filename

#!/bin/ksh

for filename in *file*; do

   #echo $filename

   fn=$filename

   if [ `ls $fn | grep -E file1` ]

   then

   echo "in if filename1 is -> $fn"

   elif [ `ls $fn | grep -E file2` ]

   then

   echo "in if filename2 is -> $fn"

   elif [ `ls $fn | grep -E file3` ]

   then

   echo "in if filename3 is -> $fn"     

   fi

done

8. Find command in Unix

find / -type f -exec grep -l "a_nwm_utt_data_mth" {} \;  2>/dev/null

find / -name hostway* 2>/dev/null

windows/dos search folder for  a text

findstr /n /i /c:"stg_ool_outage_utt_dly_chc" *

9.AWK in UNIX examples

GET_FROM_DATE="#01-jun-2015 05:50:31#1433152231"

echo $GET_FROM_DATE

#01-jun-2015 05:50:31#1433152231

FROM_DATE=`echo $GET_FROM_DATE | awk -F"#" '{ print $2 }'`

echo $FROM_DATE

01-jun-2015 05:50:31

FROM_DATE_EPOCH=`echo $GET_FROM_DATE | awk -F"#" '{ print $3 }'`

echo $FROM_DATE_EPOCH

1433152231

-F is a field separator

10.CUT In Unix 

Below displays the column-2 value considering # as a field separator

a='#2#'

echo $a

#2#

echo $a | cut -f2 -d '#'

2

I hope this info helps you :). Good Luck & Happy coding :) :)