The output of the first command gets funneled into the input of the second command; that's just how pipes work in shell.
If you do sort | who that's trying to put the output from sort into the input of who, which is a command that doesn't even read anything, so it doesn't make much sense.
You got it.
You probably already know the best way to learn is to log on and play around on the computer. You're right if only two people are on (you and the admin) that you can't really test "who" very well. In that case, you can create a little test file, and do some experiments, such as:
I used "echo" to make the test.txt file. If you know how to use a Unix editor, of course use the editor instead.
With the test file, you can try out different sort options, as you are already doing with -r option.
Quote:
I am not really sure why this order of who and sort works.
Is it because you need to run who first so the sort takes
the input from the other command (who)?
Yes, that is exactly right! "who" produces the output, the "raw materials". The output from "who" enters the pipe. On the other side of the pipe, "sort" reads its input. The output from "sort" is what you finally see.
"who" does not expect any input, so it would not make sense to put "who" on the right-hand side of the pipe. "sort" HAS to have input, or have a file specified for it to operate upon. In the examples above, I showed three simple ways sort can get input (sort file, | sort, and sort < file).
Quote:
P.S. I am doing a small grading program for this same lab as well.
I will post my results later tonight. Didn't post here because I had
not yet tried anything. Should I open a new thread or post here?
Hi Gurus,
I have two big files. I need to compare the different. currently, I am using
sort file1 > file1_temp;
sort file2 > file2_tmp
diff file1_tmp file2_tmp
I can use command
grep -v -f file1 file2
just wondering which way is fast to compare two big files.
Thanks... (4 Replies)
1. The problem statement, all variables and given/known data:
Please bare in mind I am a complete novice to this and have very very basic knowledge so please keep any answers as simple as possible and explain in terms I will understand ahha :):)
I have a text file of names and test scores... (1 Reply)
1. The problem statement, all variables and given/known data:
So i'll probably get told off for this but I have a few problems and rather than clog up the whole forum I'll post them here. Please bare in mind I am a complete novice when it comes to all this and so if you help please treat me like a... (4 Replies)
Hi,
Trying to sort grep result based on timestamp of the filename.
I have the following result and want to sort them on timestampgrep -i 'ERROR' *log*2013*
s_m_xxx_xxx_xxx_xxx_xxxx.log.20130906092431:TRANSF_1_1_1> DBG_21216 Finished transformations for Source Qualifier . Total errors ... (5 Replies)
for example, I have a text file in random content inside, maybe something like this.
234234
54654
123134
467456
24234234
7867867
23424
568567if I run this command
cat "filename.txt" | sort -n | grep "^467456$" -A 1 -B 1the result is
234234
467456
568567is it possible to do this command... (2 Replies)
Hi Expert,
Kindly request for your expertise in this matter.
I have below output:
12.125.124.173,xx1.common.com
12.125.124.174,xx2.common.com
12.125.124.175,xx3.common.com
12.125.124.176,
12.125.124.177,
12.125.124.178,
12.125.124.179,xx4.common.com
12.125.124.180,xx5.common.com... (8 Replies)
can someone help me in the awk part...little confuse on that part.
The problem is this: what input each utility gets and what it does with data and what output is provides to the next utility)
history | awk '{a++}END{for(i in a){print a " " i}}' | sort -rn | grep '^'
Thanks (4 Replies)
hello folks
i have a file that have data like
/test/aa/123
/test/aa/xyz
/test/bb/xyz
/test/bb/123
in above lines i just wants to grep "aa" and "bb".
Thanks,
Bash (4 Replies)
Hello all,
I have a test file that has the format:
.....
O
3.694950 -.895050 1.480000
O
5.485050 .895050 1.480000
Ti
-4.590000 4.590000 2.960000
Ti
-2.295000 ... (5 Replies)