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Martin Hope
Jeffrey L. Roberts
Asked: 2016-04-18 00:19:49 +0800 CST
  • 8

I just ran

cat /opt/webapplications/Word/readme.log | grep -v 'Apple'

and I got the output on the cli that I was expecting, which was all the lines in readme.log that did not contain 'Apple'...

Next I ran...

cat /opt/webapplications/Word/readme.log | grep -v 'Apple' > /opt/webapplications/Word/readme.log

However, /opt/webapplications/Word/readme.log is blank.

Can anyone explain to me why this happened, or the correct way I should have gone about this?

bash grep pipe cat
Martin Hope
rustyx
Asked: 2012-03-04 14:27:02 +0800 CST
  • 10

I know cat can concatenate files, but I need to concatenate a mix of files and streams and pipe the result to another process.

To make the question more concrete, I want to concatenate cat abc.sql together with gzip -dc xyz.sql.gz and cat qvf.sql and pipe it all as a single stream to mysql.

What's the best way to achieve this?

shell pipe cat
Martin Hope
Jake Wilson
Asked: 2011-06-30 20:53:59 +0800 CST
  • 8

If one was to run the following command

cat * | grep DATABASE

the shell would spit out all the lines in * files that contained the word DATABASE in them. Is there any way to also spit out what file each line is apart of?

I tried to use the -H option for grep which according to man says print the filename for each match but in my shell it just says

(standard input):$DATABASE_FUNCTION = dothis();
bash grep cat
Martin Hope
Daniele
Asked: 2010-08-20 02:56:58 +0800 CST
  • 35

In Linux if you type cat *, you will get something like this:

line1 from file1
line2 from file1
line1 from file2
line1 from file3
line2 from file3
line3 from file3

What I would like is to display a separator among files. Something like this:
line1 from file1
line2 from file1
XXXXXXXXXXXX
line1 from file2
XXXXXXXXXXXX
line1 from file3
line2 from file3
line3 from file3

Is that easily possible with a one-liner easy to type by heart?

linux command cat