I am trying to extract common list of Organisms from different files
For example I took 3 files and showed expected result. In real I have more than 1000 files. I am aware about the useful use of awk and grep but unaware in depth so need guidance regarding it.

I want to use awk/ grep/ cut/ perl/ python to get the needful result.
File A:

Pseudomonas stutzeri A1501
Pseudomonas fragi A22
Pseudomonas fluorescens A506
Aeromonas caviae Ae398
Rickettsiella grylli
Aeromonas veronii AMC34

File B:

Rickettsiella grylli
Pseudomonas fulva 12-X
Pseudomonas extremaustralis 14-3 substr. 14-3b
Aeromonas caviae Ae398
Gallaecimonas xiamenensis 3-C-1
Pseudomonas stutzeri A1501

File C:

Pseudomonas extremaustralis
Pseudomonas fulva 12-X
Pseudomonas extremaustralis 14-3 substr. 14-3b
Aeromonas caviae Ae398
Rickettsiella grylli
Pseudomonas stutzeri A1501

Expected Result file : Common organism

Aeromonas caviae Ae398
Pseudomonas stutzeri A1501
Rickettsiella grylli

Hoping for your suggestions and support.
Thank you in advance

If there is maximum of 1 entry per file:

awk '++A[$0]>=ARGC-1' file*

awk '{$1=$1} ++A[$0]>=ARGC-1' file*

( 
  set -- file*
  for f
  do
    cat "$f"
  done | awk '{$1=$1} ++A[$0]>=c' c=$# 
)

Try this

$ cat file?|sort|uniq -c|sort -rnb|grep "^ *3"| cut -d" " -f8-30
Rickettsiella grylli
Pseudomonas stutzeri A1501
Aeromonas caviae Ae398

A simple while loop will do the work for you

file_count=$(ls -lrt file? |wc -l)
sort -u file1 > temp;cat temp > file1;rm temp
while read i
do
result_count=$(grep -lw "$i" file? | wc -l)
if [ $result_count -eq $file_count ]; then
 echo $i
fi
done < file1

Hi Sathyaonnuix,

The solution shared by you is very impressive..... but in case if file1 has same lines multiple times (which is common to other files as well) then it will result in multiple occurrence of that line in output.
Maybe we can use sort and unique to overcome this little problem somewhat like:

cat file1|sort|uniq > tmp.tmp

Hello Mukul,
Thanks for your feedback. When grep -l command is used, it suppresses the repetition.

# cat file
repeat
repeat
repeat
123
456
567

# grep -lw repeat file
file

Hi sathyaonnuix,
Consider the below scenario :

cat filea
line1
line2
repeat1
line3
repeat2
line4
repeat1

cat fileb
1234567
repeat1
repeat2
bbbbbb

cat filec
line1
repeat1
repeat2
line2
repeat1
line3

repeat1
repeat2
repeat1