I am using go to run a shell script using exec.command like below and I want to take an input argument using command line say i
, and my output should be based on i
, how would I do that?
i := os.Args[1:2]
out, err := exec.Command("bash", "-c", "tail -n 1 /var/log/apache2/access.log | awk '{print $i/1024}' >> mem_usage.csv").Output()
if err != nil {
fmt.Println(err.Error())
return
}
How could I use that i in the shell script?
Without i
it works fine i.e if I put $1
or $2
it works fine but I want user to give me the position of i
and then calculate accordingly.
You need to format the exec
-command string accordingly.
So ie:
fmt.Sprintf("awk '{print $%d/1024}'", i)
This gives: awk '{print $1/1024}'
for i = 1
and awk '{print $2/1024}'
for i = 2
fmt.Sprintf
takes a format string and the arguments to pass into this string and returns the formatted string. (https://golang.org/pkg/fmt/#Sprintf)
And this needs to be inserted into your exec
-command:
i := 2
awkPart := fmt.Sprintf("awk '{print $%d/1024}'", i)
out, err := exec.Command("bash", "-c", "tail -n 1 /var/log/apache2/access.log | "+awkPart+" | tee -a mem_usage.csv").Output()
You should maybe try to disassemble your command a bit more for maintainabilty, but that's not part of the question.