This question already has answers here:
How do I set a variable to the output of a command in Bash?
(15 answers)
Closed 3 years ago.
I am trying to save the specific output from a piped command to a variable.
value= ping google.de -c 20 | grep -oe \/[0-9]. | head -n 1 | tr -d [\/] | tr -d "\n\r"
This saves the average ping to the variable "value".
However when I try to further process the variable e.g. in an echo line like:
echo "The Average ping is: $variable"
The output is
The Average ping is: $variable
Even when i try to pass the value to another Variable like:
value2= $value
the result is the same.
I read that variables in bash need to be declared in a certain way, may this be the problem in this specific case?
sh or bash:
value="`ping google.de -c 20 | grep -oe \/[0-9]. | head -n 1 | tr -d [\/] | tr -d "\n\r"`"
bash:
value="$(ping google.de -c 20 | grep -oe \/[0-9]. | head -n 1 | tr -d [\/] | tr -d "\n\r")"
Related
I'm running JAVA code inside shell script
java -cp ojdbc6.jar:. javaClassName args
Is it possible to do command substitution for java output inside shell
Output of java code is an array:
[{ID:143},{Name:John},{Age:32},{Designation:Enginner},{City:Delhi},{Phone:+123 456 789},{Email:abc#gmai.com}]
I want to declare above array as variables inside the same shell-script where java code runs
ID=${ID}
Name=${Name}
Try
grep -oE '(:[^}]+)' | head -2 | tr -d ':'
Demo :
$read -r Id Name <<<$(echo '[{ID:143},{Name:John},{Age:32},{Designation:Enginner},{City:Delhi},{Phone:+123 456 789},{Email:abc#gmai.com}]' | grep -oE '(:[^}]+)' | head -2 | tr -d ':' )
$echo $Id
143
$echo $Name
John
$
I had a job to perform that involved:
grep lines from a log
find a number in the line
perform basic arithmetic on the number (say, number + 1234)
The final result is a bunch of numbers separated by a newline.
If the input was:
1000
2000
3000
Then the required output was:
2234
3234
4234
I ended up with the following command:
cat log.txt | grep "word" | cut -d'|' -f7 | cut -d' ' -f5 | xargs -n 1 bash -c 'echo $(($1 + 1234))' args
I found the xargs -n 1 bash -c 'echo $(($1 + 1234))' args snippet in an answer to this question but I don't understand the need for the final args argument that is passed in. I can change it to anything, args could be blah, but if I omit it the arithmetic fails and the output is the numbers unchanged:
1000
2000
3000
Could anyone shed some light on why args is a required argument to bash -c?
A simple awk command can do the same - in a clean way:
awk -F'|' '/word/{split($7,a," "); print a[5]+1234}' log.txt
Man bash:
-c If the -c option is present, then commands are read from the first non-option argument command_string. If there are arguments after
the command_string, they are assigned to the positional parameters, starting with $0.
So, for your case, 'args' is a placeholder that goes in $0, making your actual input go in $1.
You should be able to alter your command to:
grep "word" log.txt | cut -d'|' -f7 | cut -d' ' -f5 | xargs -n 1 bash -c 'echo $(($0 + 1234))'
This question already has answers here:
How do I use floating-point arithmetic in bash?
(23 answers)
Closed 6 years ago.
I would like to divide two numbers which were extracted from a file using the below commands
temp1= grep PERM_ALLOCATED_SIZE /log/health_eg/DBsize.txt | cut -d':' -f2 | tr -d ' '
temp2= grep PERM_IN_USE_SIZE /log/health_eg/DBsize.txt | cut -d':' -f2 | tr -d ' '
and I'm able to print this
251658240
16239740
temp1 and temp2 respectively but I could not able to perform division for the above..
Sample output:
temp=temp2/temp1(0.064)
A possible solution is using echo and bc -l:
echo "251658240/16239740" | bc -l
Output:
15.49644514013155383029
Using your example, you can do that:
temp=`echo $temp2/$temp1*0.64 | bc -l`
This question already has answers here:
How do I set a variable to the output of a command in Bash?
(15 answers)
Closed 2 years ago.
How do I assign a command output to a shell script variable.
echo ${b%?} | rev | cut -d'/' -f 1 | rev
${b%?} gives me a path..for example: /home/home1
The above command gives me home1 as the output. I need to assign this output to a shell script variable.
I tried the below code
c=${b%?} |rev | cut -d '/' -f 1 | rev
echo $c
But it didn't work.
To assign output of some command to a variable you need to use command substitution :
variable=$(command)
For your case:
c=$(echo {b%?} |rev | cut -d '/' -f 1 | rev)
Just wondering why dont you try
basename ${b}
Or just
echo ${b##*/}
home1
If you want to trim last number from your path than:
b="/home/home1"
echo $b
/home/home1
b=${b//[[:digit:]]/}
c=$(echo ${b##*/})
echo ${c}
home
Just like this:
variable=`command`
This question already has answers here:
How do I set a variable to the output of a command in Bash?
(15 answers)
Closed 1 year ago.
So, lets say I have the following command:
curl -I http://google.com | head -n 1| cut -d $' ' -f2
This will capture the http status code??
Now I want to assign this to variable.. in bash script
like output = "curl -I http://localhost:8088/tracks?key=9 | head -n 1| cut -d $' ' -f2"
or something like that..
How do I assign the response of above command to a variable called output in bash?
Thanks
You have two options (see this StackOverflow answer here):
Preferred: Surround the invocation in $()
Surround the invocation in back ticks
NOTE: back ticks are legacy, the former method is preferred.
output=$(curl -I http://google.com | head -n 1| cut -d $' ' -f2)
echo "$output";
output=`curl -I http://google.com | head -n 1| cut -d $' ' -f2`
echo "$output";