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awk command

Linux / Unix: users Command Examples

users command

I am a new Linux and Unix system user. How do I list current users on Linux or Unix-like operating system using shell prompt?
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I have a bash variable as follows:

output="$(awk -F',' '/Name/ {print $9}' input.file)"

How do trim leading and trailing whitespace from bash variable called $output? How do I trim trailing whitespace from $output?
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Linux: Find Out What Process Are Using Swap Space

The top and free command display the total amount of free and used physical and swap memory in the server. How do I determine which process is using swap space under Linux operating systems? How do I find out swap space usage of particular process such as memcached?
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Awk Find And Replace Fields Values

I have a data as follows :

foo bar 12,300.50
foo bar 2,300.50
abc xyz 1,22,300.50

How do I replace all , from 3rd field using awk and pass output to bc -l in the following format to get sum of all numbers:
12300.50+2300.50+1,22,300.50
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I have a sample data file:


This is a test.
Unix is Best.
No Linux is the Best.
Space in simple understanding is an area or volume.
Outer space .

I need the output:

Unix is Best.
Outer space .

Tutorial details
DifficultyEasy (rss)
Root privilegesNo
Requirementsawk and bash
Estimated completion timeN/A

How do I print all lines that have three (3) words only?
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I'm trying to match words using GNU awk command and getting the following error:

echo 'foo bar this that blah' | awk '{gsub("\<regex-word\>", "NEW-WORD");print}'

But getting the following warning on screen and it is not working:
awk: warning: escape sequence `\< ' treated as plain `<' awk: warning: escape sequence `\>' treated as plain `>'

How do I fix this problem under Unix like operating systems?
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Linux / Unix sed: Delete Word From File / Input

I've a file as follows:

This is a test.
One bang two three
Foo dang Bar
001 0xfg 0xA
002 0xA foo bar 0xfG
I'm done

Tutorial details
DifficultyIntermediate (rss)
Root privilegesNo
Requirementssed and bash/ksh
Estimated completion timeN/A

How do I delete all "words" from the above file which ends with a particular letter (say 'g') in each line? The output should be as follows:

This is a test.
One two three
Foo Bar
001 0xA
002 0xA foo bar
I'm done

How do I delete regex-based word using sed or awk under Linux / Unix like operating systems?
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