Sponsored Content
Top Forums UNIX for Dummies Questions & Answers Single UNIX command to display users and to count them Post 302739569 by sreyan32 on Tuesday 4th of December 2012 11:55:29 AM
Old 12-04-2012
Question

Quote:
Originally Posted by bakunin

Code:
$(( $(w| wc -l) - 2 ))

bakunin
Thank You so much for your detailed explanation. But I have some doubts-:

1) In the following code-:

Code:
$(( $(w| wc -l) - 2 ))

Why have you used two opening and two closing brackets for the outer expression and only one opening and one closing for the inner expression that is-:

Code:
$(w| wc -l)

I tried it with two opening and closing brackets for both inner and outer expression and I keep getting errors. Same thing if I try with one bracket for both inner and outer expressions.Why does it only work like the way that you have specified ?

2) When we use tee the stream is duplicated and by default the first stream is always printed out. Am I right in assuming this ? Or is there a way to control the output of both the divided streams?

3)The duplicate stream that tee creates is also an output stream. And we redirect that second duplicate stream to the following operations-:

Code:
(cut -d\  -f1|uniq | wc -l >/dev/stderr )

But then if there is already an output stream then why are we redirecting the output to the error stream ?

By the way do you know what the following command does-:

Code:
kill $!

I searched for it in Google but I did not get any such answer. I just don't want to open up another thread for only such a small topic. If you do know the answer then please let me know.

Thank You again for your explanation. It did help a lot.
 

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

How to use more than one MPE command STREAM with Unix command in a single shell?

Hello, I have problem in writing the shell script involving MPE command STREAM related to HP-UX and Unix command. Script is sh "nlshCMD 'STREAM <job name1>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name2>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name3>' |... (0 Replies)
Discussion started by: bosskr
0 Replies

2. HP-UX

How to use more than one MPE command STREAM with Unix command in a single shell?

Hello, I have problem in writing the shell script involving MPE command STREAM related to HP-UX and Unix command. Script is sh "nlshCMD 'STREAM <job name1>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name2>' | 'SHOWJOB' | grep $HPJOBNUM" sh "nlshCMD 'STREAM <job name3>' |... (1 Reply)
Discussion started by: bosskr
1 Replies

3. UNIX for Dummies Questions & Answers

run command Unix on a single line

Hi everybody.. I need to enter in bash mode and then run a command and this just in a single command line. I tried : "bash ^M| somecommand" but nothing.. How do I do to simulate the return button just right after the bash command ? Thanks.. (8 Replies)
Discussion started by: Riddick61
8 Replies

4. Shell Programming and Scripting

Need a Command To display "echo command value in loop" in single line.

Hi I want to display "echo command value in loop" in single line. My requirement is to show the input file (test_1.txt) like the output file (test_2.txt) given below. Input file :test_1.txt a1|b1|4|5 a1|b1|42|9 a2|b2|32|25 a1|b1|2|5 a3|b3|4|8 a2|b2|14|6 Output file:test_2.txt... (2 Replies)
Discussion started by: sakthifire
2 Replies

5. UNIX for Dummies Questions & Answers

Re: How To Use UNIQ UNIX Command On single Column

Hi , Can You Please let Know How use unix uniq command on a single column for deleting records from file with Below Structure.Pipe Delimter File . Source Name | Account_Id A | 101 B... (2 Replies)
Discussion started by: anudeepkumar123
2 Replies

6. Shell Programming and Scripting

History of all the users in single file with command , date . time , ip and user

HTML Code archive_history() { HISTORYOLD=${HISTFILE}.archive CURTIME=`date` CURTTY=`tty` IP=$(echo $SSH_CLIENT | awk '{print $1}') if ; then echo "#-${HOSTNAME}-- ${CURBASHDATE} - ${CURTIME} ($CURTTY) ${USER} ${IP}----" >> $HISTORYOLD history... (2 Replies)
Discussion started by: rehantayyab82
2 Replies

7. Shell Programming and Scripting

History of all the users in single file with command , date . time , ip and user

HTML Code: archive_history() { HISTORYOLD=${HISTFILE}.archive CURTIME=`date` CURTTY=`tty` IP=$(echo $SSH_CLIENT | awk '{print $1}') if ; then echo "#-${HOSTNAME}-- ${CURBASHDATE} - ${CURTIME} ($CURTTY) ${USER} ${IP}----" >> $HISTORYOLD history... (0 Replies)
Discussion started by: rehantayyab82
0 Replies

8. UNIX for Dummies Questions & Answers

To find and display the middle line in a file using single line command.

Hi all, How can i display the middle line of a file using a single line command? (6 Replies)
Discussion started by: Lakme Pemmaiah
6 Replies

9. UNIX for Beginners Questions & Answers

Get count of multiple word in single command

Hello Experts, I have a log file that contains 4 different type of exception : 1- Exception 2- Fatal 3- Error 4- Exec My requirement is to find count of each type of exception, i tried using combination of -E and -C but that doesn't seems to be working : grep -ec 'Exception' -ec... (4 Replies)
Discussion started by: mukulverma2408
4 Replies

10. UNIX for Beginners Questions & Answers

How to find the count of IP addresses that belong to different subnets and display the count?

Hi, I have a file with a list of bunch of IP addresses from different VLAN's . I am trying to find the list the number of each vlan occurence in the output Here is how my file looks like 1.1.1.1 1.1.1.2 1.1.1.3 1.1.2.1 1.1.2.2 1.1.3.1 1.1.3.2 1.1.3.3 1.1.3.4 So what I am trying... (2 Replies)
Discussion started by: new2prog
2 Replies
FFLUSH(3)						   BSD Library Functions Manual 						 FFLUSH(3)

NAME
fflush, fpurge -- flush a stream LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <stdio.h> int fflush(FILE *stream); int fpurge(FILE *stream); DESCRIPTION
The function fflush() forces a write of all buffered data for the given output or update stream via the stream's underlying write function. The open status of the stream is unaffected. If the stream argument is NULL, fflush() flushes all open output streams. The function fpurge() erases any input or output buffered in the given stream. For output streams this discards any unwritten output. For input streams this discards any input read from the underlying object but not yet obtained via getc(3); this includes any text pushed back via ungetc(3). RETURN VALUES
Upon successful completion 0 is returned. Otherwise, EOF is returned and the global variable errno is set to indicate the error. ERRORS
[EBADF] stream is not an open stream, or, in the case of fflush(), not a stream open for writing. The function fflush() may also fail and set errno for any of the errors specified for the routine write(2). SEE ALSO
write(2), fclose(3), fopen(3), setbuf(3) STANDARDS
The fflush() function conforms to ANSI X3.159-1989 (``ANSI C89''). BSD
June 4, 1993 BSD
All times are GMT -4. The time now is 06:59 PM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy