5

Order of redirections

view full story
linux-howto

http://unix.stackexchange.com – I don't quite understand how the computer reads this command. cat file1 file2 1> file.txt 2>&1 If I understand, 2>&1 simply redirect Standard Error to Standard Output. By that logic, the command reads to me as follows: concatenate files file1 and file2. send stdout from this operation to file.txt. send stderr to stdout. end? I'm not sure what the computer's doing. By my logic, the command should be cat file1 fil2 2>&1 > file.txt but this is not correct. (HowTos)

Danial's picture
Submitted by Danial on 04/30/2012 – Made popular on 04/30/2012

Stories similar to Order of redirections

I always run my shell with a command:

./shellName file1 file2

So, in the shell, I can refer file1 as $1 and file2 as $2. However, if I want to run the shell with this command

./shellName < file1 > file2

I tried to read the file1 as standard input and file 2 as standard output. How can I refer file1 and file2 in the shell script? Can I still use $1 and $2? Thanks in advance.

Help regarding grep command 25 weeks 6 days ago

Hi ,

I have two files File1 and File2.In First file i have table names abc def cfg

In second file i have the sql commands for e.g replace view def.test1 for access select * from abc.test1;

I have to find the common words from File1 and File2 and printing it in File3 the grep command i am using is

grep -o -f File1 File2|sort|uniq > File3

The problem i am facing is , if i run the above g

How can I set up this loop? 32 weeks 5 days ago

I want to compare two files. I think using grep is the way to go but I do not know how to set this up. Let me show an example: File1 has 1000 items, File2 has 700 items I need to take the first item in File1 and search the entire contents of File2 to see if there is a match there. IF there is a match (meaning the same item is in both File1 and File2) then do nothing.

I have file1 and file2 I lookup field3 from file2 in field1 of file1 and if there is a match, output field 2,3,5 from file2. I now want to add field2 of file1 in the output.

I suspect what I have to do is read the entire line of file1 into a 2 dim array? pls help.

Hi All,

I have two files in the directory file1.txt file2.txt

I gave ls -m > output.txt command and I got the output as file1.txt, file2.txt, output.txt

But my output should be like

file1.txt, file2.txt

Thanks in advance.

I have two files,

file1.txt: 1 abc 2 def 2 dgh 3 ijk 4 lmn

file2.txt 1 opq 2 rst 3 uvw

My desired output is: 1 abc opq 2 def rst 2 dgh rst 3 ijk uvw

I have tried using the 'join' command (ie. 'join file1.txt file2.txt') but it returns the error that file1.txt is not sorted because of the repeated value (ie. 2).

Does anyone know how to solve this? Thanks!

I piped my own shell scripts for some testing and accidentally noticed something strange.

Hi Freinds,

i have a file1 as below file1

Code:

1|ndmf|fdd|d3484|34874 2|jdehf|wru7|478|w489 3|dfkj|wej|484|49894 file2 contains lakhs of records and not in sorted order i want to retrive only the records from file2 by searcing the first field of file 1

i used

Code:

grep ^1 file2 >out.txt grep ^2 file2 >>out.txt grep ^3 file2>>out.txt this i need to do 3 time

Hi Everyone!

I would like ask if there's a better way I can delete multiple lines in a file1 by collecting all criteria from file2.

file1: a b c d e f

file2: a e f

The expected value will be: b c d

The code below seems to work however if is taking much time when dealing with huge records.