Using Ubuntu.
Currently I'm trying to add a user inputted variable to the end of a file.
In short, this allows me to use a BASH script to automate adding VSFTPD users.
Currently I have used awk & sed.
I don't have the sed but here is my awk that I currently have together.
awk '{$centre_name}' /etc/vsftpd-users
GNU AWK solution
You might use -v to ram variable into GNU AWK, I would do it following way, let file.txt content be
1
2
3
then
var1="four"
awk -v var=${var1} '{print}END{print var}' file.txt
gives output
1
2
3
four
Explanation: I use -v to set awk's variable var value to value of shell's variable var1 then each line of file I just print as-is, after processing is done I do print value of var.
(tested in gawk 4.2.1)
GNU sed solution You might use $ to target last line and use command a for append line of text as follows, for file.txt shown earlier
var1="four"
sed "$ a ${var1}" file.txt
gives same output as above
(tested in GNU sed 4.5)
Related
I am trying to capture the string between 2 specific letters/words using sed/awk. This is what I am trying to do:
The input is a file test.log containing
Owner: CN=abc.samplecerrt.com,o=IN,DC=com
Owner: CN=abc1.samplecerrt.com,o=IN,DC=com
I want to extract only "CN=abc.samplecerrt.com"
I tried
sed 's/.*CN=\(.*\),.*/\1/p' test.log >> result.log
But this returns "abc.samplecerrt.com,o=IN,DC=com"
How do I go about this?
test file:
$ cat logs.txt
CN=abc.samplecerrt.com,o=IN,DC=com Owner: CN=abc1.samplecerrt.com,o=IN,DC=com
command and output:
$ grep -oP 'CN=(?:(?!CN=).)*?.com' logs.txt
CN=abc.samplecerrt.com
CN=abc1.samplecerrt.com
This might work for you (GNU sed):
sed -n 's/.*\(CN=[^,]*\).*/\1/p' file
Or:
sed 's/.*\(CN=[^,]*\).*/\1/p;d' file
The first turns off implicit printing -n so as to act like grep.
Matches and captures the string CN= followed by zero or more non-comma characters and prints the captured group \1 if a match is made.
The second solution is much the same except it deletes all lines and only prints the captured group as above.
With awk you can get the field where is the string you need. For it, you can set FS=:|, Now if you run
awk -v FS=":|," '{print $2}' file
CN=abc.samplecerrt.com
CN=abc1.samplecerrt.com
you get the field. But you only want one, so
awk -v FS=":|," '$2 !~ /abc1/ {print $2}' file
CN=abc.samplecerrt.com
I need to print the string between these characters....
atob(' ')
I am using a = in the second part as an attempt to stop the code on an equal signs (which the base64 string I'm trying to get ends in.)
I use this script, but it prints the entire line containing the above characters. I need just the data in between.
sed -n '/atob/,${p;/==/q;}'
I appreciate any help. Thank you.
Does this work (tested for GNU sed 4.2.2)?
sed -n -e "s/atop('\(.*\)')/\1/p" b.txt
where b.txt is
atop('safdasdfasf')
or you can try awk
awk -F\' '/atop/ {print $2}' b.txt
(tested for gnu awk 4.0.2 and added the suggestion by Jotne)
And another working sed:
echo "atop('safdasdfasf')" | sed -r "/atop/ s/^[^']+'([^']+)'.*/\1/"
safdasdfasf
I am new to shell scripting and I'm very confused between awk -FS and awk -f commands used. I've tried reading multiple pages on the difference between these two but was not able to understand clearly. Kindly help.
Here is an example:
Lets consider that a text file say, data.txt has the below details.
S.No Product Qty Price
1-Pen-2-10
2-Pencil-1-5
3-Eraser-1-2
Now, when i try to use the following command:
$ awk -f'-' '{print $1,$2} data.txt
I get the below output:
1 Pen
2 Pencil
3 Eraser
But when i use the command:
$ awk -FS'-' '{print $1,$2} data.txt
the output is:
1-Pen-2-10
2-Pencil-1-5
3-Eraser-1-2
I don't understand the difference it does using the -FS command. Could somebody help me out on what exactly happens between these two commands. Thanks!
You are more confused than you think. There is no -FS.
FS is a variable that contains the field separator.
-F is an option that sets FS to it's argument.
-f is an option whose argument is the name of a file that contains the script to execute.
The scripts you posted would have produced syntax errors, not the output you say they produced, so idk what to tell you...
-FS is not an argument to awk. -F is, as is -f.
The -F argument tells awk what value to use for FS (the field separator).
The -f argument tells awk to use its argument as the script file to run.
This command (I fixed your quoting):
awk -f'-' '{print $1,$2}' data.txt
tells awk to use standard input (that's what - means) for its argument. This should hang when run in a terminal. And should be an error after that as awk then tries to use '{print $1,$2}' as a filename to read from.
This command:
awk -FS'-' '{print $1,$2}' data.txt
tells awk to use S- as the value of FS. Which you can see by running this command:
awk -FS'-' 'BEGIN {print "["FS"]"}'
I am writing a small script to map all the current memory being used by services running in a server. However, I am facing a problem doing that. My script is quite simple. I'm using pmap to find out memory being used and trying add up all the pid of a service running.
#!/bin/bash
result=`$pgrep java`
wc=`$pmap -x $result | wc -l`
gawk=`$pmap -x $result | gawk 'NR==$wc{print $3}'`
echo "$gawk"
Now, my problem is that gawk uses single quote when searching for a specific pattern (gawk 'NR==$wc{print $3}') but shell script gives me error because then meaning of single quote is different in shell from gawk.
Based on your comment, it looks like you're trying to do this:
pmap -x "$(pgrep java)" | awk '{s=$3}END{print s}'
This prints the third column of the last line of the output of pmap -x, with the PID of the running java process. In some versions of awk, you can simply do 'END{print $3}' but this isn't guaranteed to work.
pmap -x $result | gawk 'NR==$wc{print $3}' is not doing what you think it is. (I have replaced your $pmap with pmap, but my analysis is only of the gawk command so if that is incorrect it should be irrelevant.) The shell is going to pass the literal string NR==$wc{print $3} to awk, but it appears that you want awk to see the value of the shell variable $wc rather than the literal string $wc. When awk sees $wc, it treats wc an an uninitialized value, so $wc become equivalent to $0, and awk will print any line whose content matches the line number. The standard way to pass the shell variable into awk is:
pmap -x $result | gawk 'NR==w{print $3}' w=$wc
This assignes the shell variable wc to the awk variable w, and will print the third column of that line.
Note that there are a number of issues with this shell script, but this seems to be the core confusion.
How can I extract word between 2 words in a file using cut and awk command.
Lets say: I have a file with below content.
This is my file and it has lots of content along wiht password and want to extract PASSWORD=MYPASSWORDISHERE==and file is ending here.
exptected output
1) using awk command linux.
2) using cut command linux.
MYPASSWORDISHERE==
Using awk actually gawk
awk '{match($0,/PASSWORD=(.*==)/,a); print a[1];}' input.txt
Using cut you can try, I'm not sure if it works with your file
cut -d"=" -s -f2,3 --output-delimiter="==" input.txt