Both these assumptions do not stand up to benchmark testing except perhaps on the first use of "cat" after a clean boot.
Don't be ridiculous.
Code:
$ time for ((N=0; N<10000; N++)) ; do cat config | grep 32 > /dev/null ; done
real 0m21.712s
user 0m7.800s
sys 0m14.561s
$ time for ((N=0; N<10000; N++)) ; do grep 32 < config > /dev/null ; done
real 0m14.115s
user 0m5.932s
sys 0m9.381s
$
...and this is on a dual-core system. If grep had to time-share with cat, the performance would be worse yet. There is of course a cost in resources and time to launching a process and piping data through it, especially for small amounts of data. It's only insignificant when you do it once.
Last edited by Corona688; 09-15-2010 at 02:58 PM..
hi everybody,
how do i open a txt file writen in unix on to a web page
so when i want to view the txt file that was generated from a shell program, that file is open on a web page
do i use the cat > filename.html command to do this, or is there another way
many thanks
:D (2 Replies)
I would like to append some statement into 1 single file so that it can be concatenate together in 1 word. I have tried >> but it will seperate my 2 statement into 2 rows.
# cat abc.txt cde.txt > result.txt
where abc.txt is "abcde" and cde.txt is "12345"
the result should come out as... (3 Replies)
Dear All
I have two text files File1.txt and File2.txt . I am concatenating the two files and making it as single file Cat_File.txt. Now i need to keep joined file in two different path. that is I need to use cat command only once ,but store joined file in two different locations. Since... (3 Replies)
Hello,
So I sorted my file as I was supposed to:
sort -n -r -k 2 -k 1 file1 | uniq > file2
and when I wrote
> cat file2
in the command line, I got what I was expecting, but in the script itself
...
sort -n -r -k 2 -k 1 averages | uniq > temp
cat file2
It wrote a whole... (21 Replies)
I believe I used the cat command to append a file beside another file (instead of below it) but I did not document it any where and I can't remember exactly how I did it. Has anyone else done this? I have tried all the cat options individually with no luck. It may be a combination of options.
... (2 Replies)
I want to concatenate 100 files to one file and append file name in each record to find out which file it came from
for a in $(<shal_group)
do
cat $a >> bigoutput.group
The above code put all files in one file but i want file name appended to each file
Record should be like this... (3 Replies)
I have a file "sample.txt" with the content as below:
Hi
This is a Sample Text.
I need a single command using cat which serve the following purpose.
1.display the contents of sample.txt
2.append some text to it
3. and then exit
But, all should be served by a sinle... (1 Reply)
Discussion started by: ashok.g
1 Replies
LEARN ABOUT CENTOS
write
WRITE(1) User Commands WRITE(1)NAME
write - send a message to another user
SYNOPSIS
write user [ttyname]
DESCRIPTION
Write allows you to communicate with other users, by copying lines from your terminal to theirs.
When you run the write command, the user you are writing to gets a message of the form:
Message from yourname@yourhost on yourtty at hh:mm ...
Any further lines you enter will be copied to the specified user's terminal. If the other user wants to reply, they must run write as
well.
When you are done, type an end-of-file or interrupt character. The other user will see the message EOF indicating that the conversation is
over.
You can prevent people (other than the super-user) from writing to you with the mesg(1) command. Some commands, for example nroff(1) and
pr(1), may disallow writing automatically, so that your output isn't overwritten.
If the user you want to write to is logged in on more than one terminal, you can specify which terminal to write to by specifying the ter-
minal name as the second operand to the write command. Alternatively, you can let write select one of the terminals - it will pick the one
with the shortest idle time. This is so that if the user is logged in at work and also dialed up from home, the message will go to the
right place.
The traditional protocol for writing to someone is that the string `-o', either at the end of a line or on a line by itself, means that
it's the other person's turn to talk. The string `oo' means that the person believes the conversation to be over.
SEE ALSO mesg(1), talk(1), who(1)HISTORY
A write command appeared in Version 6 AT&T UNIX.
AVAILABILITY
The write command is part of the util-linux package and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/.
util-linux March 1995 WRITE(1)