Simple Unix Commands AWK, SED etc....

Find files greater than 1M

$> find . -depth -xdev -size +1000000c -print

Delete files older than 3 days

$> find . -mtime +3 -print -exec rm * {} ;

To find out what is running on a port

$> lsof -i tcp grep port number

Change contents of file from lower case to upper case

$> cat x.lst tr [a-z] [A-Z] > x.sql

AWK COMMANDS

To print the first two fields in opposite order, enter:

$> awk '{ print $2, $1 }' chapter1

To display all lines between the words start and stop, including "start" and "stop", enter:

$> awk '/start/,/stop/' chapter1

To run an awk command program, sum2.awk, that processes the file, abc1, enter:

$> awk -f sum2.awk abc1

contents of file ‘abc1’
2 2 2 2
3 3 3 3
4 4 4 4
5 5 5 5
------- Start of Program sum2.awk ------
{
sum += $2
}
END {
print "Sum: ", sum;
print "Average:", sum/NR;
}
------- End of Program sum2.awk ------
Explanation: The first action adds the value of the second field of each line to the variable sum. All variables are initialized to the numeric value of 0 (zero) when first referenced. The pattern END before the second action causes those actions to be performed after all of the input file has been read. The NR special variable, which is used to calculate the average, is a special variable specifying the number of records that have been read.

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Repeat everyline in the file and prefix it with some word

Example :

Source : a.sh

abc
def
ghi

Output : b.sh

echo abc
tnsping abc
echo def
tnsping def
echo ghi
tnsping ghi

Solution

for line in `cat a.sh`
do
echo echo "$line"
echo tnsping $line
done >> b.sh

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Bring the 1st line at the end of 2nd line and then 3rd line at the end of 4th line and so on…..

Example :

Input

ADMINDB1
SYSTEM/manager@
ADSERVD1
SYSTEM/manager@

Output

SYSTEM/manager@ADMINDB1
SYSTEM/manager@ADSERVD1

Solution

awk 'NR % 2 == 0' testfile > file1
awk 'NR % 2 ' testfile > file2
paste file1 file2 tr -d 't'

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