Searching a file name in file using SHELL SCRIPT

Question

I will fetch the file names from the file say: FILE_A, and will search these file names in another file say: File_B Using the script say: script.sh

I want to print those file names which are not present in a file say: FILE_B. I use the code but it didn't work.

Code in the script->script.sh is as follows:

#!/bin/bash
while read line

do
       grep -v "$line" FILE_B

done<FILE_A

please help me. why it is not working and what is the solution of it?

very inefficient to grep file_b for every line in file_a – glenn jackman Feb 23 '14 at 18:56 — glenn jackman, Feb 23 '14 at 18:56

score 2 · Answer 1 · answered Feb 23 '14 at 18:51

2

grep can read its input from a file; no need for a loop.

grep -Fxvf FILE_A FILE_B

The -F option specifies that the input is literal strings, not regular expressions. Otherwise an input which contains regex metacharacters would not match itself; or not only itself. For example, the regular expression a.c matches "aac", "abc", etc.

The -x option requires a full-line match. Otherwise, the input "bc" would match on any line containing it as a substring, such as "abcd".

The -v option says to print non-matching lines instead of matching.

Finally, the lowercase -f option specifies a file name as its argument to use as input for the patterns to match.

answered Feb 23 '14 at 18:51

tripleee

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It is not giving the output though the command is running, your answer need some more addition/modification to print it. Please reply. – ANUJ GUPTA Mar 11 '14 at 06:20
I can reply but not really help without more information. It works for me. http://pastebin.com/9y2YvwEN – tripleee Mar 11 '14 at 07:42
but it is not working in my environment, the sample u shown over pastebin(link mention in the reply), i need it be working as similar. if u know why it is not working then please share the information. – ANUJ GUPTA Mar 13 '14 at 10:29
I'll write this slowly: If you don't provide additional information, we can only guess. DOS line feeds? Cosmic rays? Voices inside your head? – tripleee Mar 13 '14 at 10:35
Try this: http://pastebin.com/PZdwWSzt – tripleee Mar 13 '14 at 10:54

score 1 · Answer 2 · answered Feb 23 '14 at 18:55

1

comm is good for this, but it requires the input files to be sorted. If that's not a problem:

# lines in FILE_A that are not in FILE_B
comm -23 <(sort FILE_A) <(sort FILE_B)

answered Feb 23 '14 at 18:55

glenn jackman

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i checked it and it is working – ANUJ GUPTA Mar 18 '14 at 06:48

score 0 · Answer 3 · answered Feb 23 '14 at 08:33

0

This script works but does not print what you want. For each filename in FILE_A it prints all the OTHER filenames in FILE_B. Instead you should print the filename yourself if grep does not find it:

while read line
do
  grep "$line" FILE_B >/dev/null || echo "$line"
done <FILE_A

answered Feb 23 '14 at 08:33

SzG

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grep should also add -w parameter to check full file names instead of just blind text searching...right? – Ankit Kumar Feb 23 '14 at 08:41
If each line is a pure filename, it does not make any difference. – SzG Feb 23 '14 at 08:43
yes as u said it used to do the same, u can try above solution that i have verified – ANUJ GUPTA Mar 11 '14 at 06:09

score 0 · Accepted Answer · answered Feb 23 '14 at 08:37

0

No extra linefeed between while and do
grep -v expr file will print all lines of those files, not containing expr. What you want, is just the result whether it's found or not. You need to test the exit state.

Try:

#!/bin/bash
while read line
do
       grep -q "$line" FILE_B || echo "$line"

done<FILE_A

grep returns exit 0 if a line was found. The || concatenation with echo means: execute echo when exit state != 0- i.e. when $line was not found.

answered Feb 23 '14 at 08:37

Axel Amthor

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grep should also add -w parameter to check full file names instead of just blind text searching...right? – Ankit Kumar Feb 23 '14 at 08:39
TBD: what, if filename is only part of the line? OP does not post any requirements about these details. – Axel Amthor Feb 23 '14 at 08:41
no, let say if the filename in file_A is file123 and there is a file "file12345" in file_B then to handle such cases, -w is required – Ankit Kumar Feb 23 '14 at 08:44
still TBD: could also be `-x`- hole line. Unclear – Axel Amthor Feb 23 '14 at 09:17
I WANT PRINT ALL LINE of those files, not containing expr – ANUJ GUPTA Mar 11 '14 at 05:55
your answer is correct as i needed but i didn't understood why -v didn't work as if i tried it normally it works, why not in the loop of script, please reply – ANUJ GUPTA Mar 11 '14 at 06:28

score 0 · Answer 5 · answered Feb 23 '14 at 08:38

0

Use this instead

#!/bin/bash
while read line
do
    if grep -qw $line "file_B"
    then
    echo $line
    fi
done < file_A

answered Feb 23 '14 at 08:38

Ankit Kumar

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It prints the file name which are present in FILE_B I need to print only all those file names which are not present in FILE_B. your ans needs some modifications. Please reply. – ANUJ GUPTA Mar 11 '14 at 06:03
It prints the file name which are present in FILE_B I need to print only all those file names which are not present in FILE_B. your ans needs some modifications. Please reply. – ANUJ GUPTA Mar 11 '14 at 06:10

Searching a file name in file using SHELL SCRIPT

5 Answers5