Executing a command

Question

I'm trying to execute a command:

public static void main(String[] args) { int buffer; StringBuilder res = new StringBuilder(); Process proc; try { proc = Runtime.getRuntime().exec("cat /proc/stat | grep 'btime' | awk '{print $2}'"); BufferedReader reader = new BufferedReader(new InputStreamReader(proc.getErrorStream())); String line; while ((line=reader.readLine())!=null) { System.out.println(line); } proc.waitFor(); } catch (Exception e) { e.printStackTrace(); } }

But the result is not what I expected:

cat: '|': No such file or directory cat: grep: No such file or directory cat: "'btime'": No such file or directory cat: '|': No such file or directory cat: awk: No such file or directory cat: ''\''{print': No such file or directory cat: '$2}'\''': No such file or directory

What am I doing wrong? Ubuntu 18.04.

Runtime.exec cannot run arbitrary shell/terminal commands like this. — Teddy
– Teddy, Commented Nov 17, 2018 at 16:49
Possible duplicate of: stackoverflow.com/questions/15356405/… — Teddy
– Teddy, Commented Nov 17, 2018 at 16:52

Teddy · Accepted Answer · 2018-11-17 16:51:43Z

Runtime.exec cannot run arbitrary shell/terminal commands like this.

You have to run the bash program and then send your command as parameter to bash. Bash will do the job for you.

https://stackoverflow.com/a/15356451/1364747

This is OS specific. On a different OS it might be a different command/terminal. Also you might need to know the path to that program.

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