This question already has answers here:
Capturing multiple line output into a Bash variable
(7 answers)
Closed 3 years ago.
I have a small script where I appended the output of linux mpstat to a log file.
#/bin/bash
CPU_USAGE=$(mpstat)
echo $CPU_USAGE >> temp.log
The problem is that the output of mpstat on the terminal is formatted properly in 3 lines like so
However, the output to the file is all in one line.
How do I format the output like the one on the terminal?
Just quote the variable so it is not seen as several different parameters to be printed one after the other:
echo "$CPU_USAGE" >> temp.log
You could just directly pipe the output to the file:
#!/bin/bash
mpstat >> temp.log
If you must store it in a variable, then quote it like:
#!/bin/bash
CPU_USAGE=$(mpstat)
echo "$CPU_USAGE" >> temp.log
Otherwise, bash will not interpret the newlines as part of the message to echo, but the whole output as a list of short strings to output.
Related
This question already has answers here:
Use key/value data from a file in a shell script
(1 answer)
Reading key/value parameters from a file into a shell script
(1 answer)
Closed 3 years ago.
$ cat foo.txt
a=1one
b=2two
c=3 three
d=4four
$ source foo.txt
bash: three: command not found...
Need to set all the variable listed in foo.txt, how to source this file by escaping the space character? foo.txt comes from other application, which I cannot control, or is there an alternative to source ?
If the output is so regular, you could try to preprocess the file using sed like this:
$ sed -e "s/=/='/;s/$/'/" < foo.txt >sourced.env
and then source sourced.env. This will add a ' just after the = and add an ending '.
This question already has answers here:
How do I properly quote this bash pipeline for watch?
(2 answers)
Closed 3 years ago.
How can I echo this entire piece of code to .bashrc without leaving out a single character?
# automatic logging of terminal input/output
test "$(ps -ocommand= -p $PPID | awk '{print $1}')" == 'script' || (script -f -q /home/user/.logs/terminal/manjaro/$(date +"%Y-%m- %d_%H:%M:%S")_terminal.log)
When I attempt to enter the following into terminal:
echo "the above code" >> ~/.bashrc
I get the following appended to .bashrc which is nothing like "the above code", its short about 45 or so characters.
# automatic logging of terminal input/output
test script == 'script' || (script -f -q /home/user/.logs/terminal/manjaro/2019-05- 08_09:09:19_terminal.log)
As you can see, it's leaving out A LOT of the original code. I understand this has a lot to do with the number of different quotations and placement, but without altering my code much, or at least to the point where it can still function as its intended, how can I go about getting this to echo to the file properly?
Thank you for every nanosecond of your time.
Wrap your echo'd string with single quotes ' instead of double "
This question already has answers here:
Variables overwriting text problem with "echo" in Bash
(2 answers)
Closed 4 years ago.
I wrote a script to change .CSV to json.
#!/bin/bash
exec 0< example.csv
while IFS=, read name element input decrease
do
echo "${element}decrease: ${decrease}test"
done
the example.csv I paste here
name1,A,11,12
name2,B,13,14
But the output is really weird...
testrease: 12
testrease: 14
As u can see, The test rewrite Adecrease and Bdecrease, makes them to testrease.
I can't believe it!! So I tried with out exec 0< example.csv, type them in stdin, this time I got what I want
name1,A,11,12
Adecrease: 12test
So I guess maybe there are some characters in example.csv I can't see which makes this problem. I use cat -v example.csv
name1,A,11,12^M
name2,B,13,14^M
Nothing strange and I stuck here.
I am very new to shell script, so if anyone can give me some suggestions I will be really thrilled!!
Thank u, #chepner! tag wiki saves me another hour on this stupid question.
And here is the solution from wiki:
Check whether your script or data has DOS style end-of-line characters.
Use cat -v yourfile or echo "$yourvariable" | cat -v.
DOS carriage returns will show up as ^M after each line.
If you find them, delete them using dos2unix (a.k.a. fromdos) or tr -d '\r'.
This question already has answers here:
Passing arguments to an interactive program non-interactively
(5 answers)
Closed 7 years ago.
So suppose a normal command run in terminal goes like this....
user$ thecommand
Please enter your first name:
>
and then waits for your to type your name... straightforward, but if in a bash script I try and do something like:
#! /bin/bash
echo "What is your name?"
read name
thecommand
how would I have THE SCRIPT enter "$name" in response to "thecommand" instead of having the user manually input it themselves?
you can add input by pipe like this:
echo yourname | ./yourscript
for more inputs you can use printf
printf "input1\ninput2" | ./yourscript
where \n means new line and it will be used like new input.
Run your script like:
./yourscript.sh < file.txt
where file.txt will contain the name.
now your script will look for name from the file(file.txt), in file.txt you can type the names which will act as input for read command.
read command reads on line at a time so if u have more than on read command in your script you should have multiple lines in file.txt file
For complicated cases, for example if your input depends on the output of your command, you may write an "expect" script.
To see how it works you can auto-generate such script interactively
$ autoexpect thecommand
And then run it
$ expect -f script.exp
This question already has answers here:
Capturing multiple line output into a Bash variable
(7 answers)
Closed 5 years ago.
I'm trying to capture a block of text into a variable, with newlines maintained, then echo it.
However, the newlines don't seemed to be maintained when I am either capturing the text or displaying it.
Any ideas regarding how I can accomplish this?
Example:
#!/bin/bash
read -d '' my_var <<"BLOCK"
this
is
a
test
BLOCK
echo $my_var
Output:
this is a test
Desired output:
this
is
a
test
You need to add " quotes around your variable.
echo "$my_var"