System command fail to execute from program

Question

I had tested the following methods to execute Linux command from my program

Method 1 : Assign all into a string

String temp1 = "'/"+t2+"/,/"+t1+"/p'";
String command2 = "sed -n "+temp1+" app.log";
Process p1 = Runtime.getRuntime().exec(command2);

Method 2 : use array

String [] command2 = new String []{"sed","-n","'/",t2,"/,/",t1,"/p'", "app.log";
System.out.println("The command2 is : "+Arrays.toString(command2);
Process p2 = new ProcessBuilder(command2).start();

This my reference link for the method 2 but both of the methods not working at all. This is the command I hope to run in the terminal
sed -n '/14:32:54/,/14:33:44/p' app.log

This is a portion of my code for calling the system command, nothing displayed in line2 variable

String [] command2 = new String []{"sed","-n","'/",t2,"/,/",t1,"/p'","stlog.txt"};
Process p2 = new ProcessBuilder(command2).start();
BufferedReader br2 = new BufferedReader(new InputStreamReader(p2.getInputStream()));
String line2;
while((line2 = br2.readLine()) != null)
   {
      System.out.println(line2);
   }

Won't the above execute sed -n '/ t2 /,/ t1 /p' stlog.txt, ie with a whole lot of unnecessary spaces in your regex, or even worse, pass in seven parameters to sed? "sed","-n","'/"+t2+"/,/"+t1+"/p'","stlog.txt" might be one quick solution. — Ken Y-N
– Ken Y-N, Commented Jun 1, 2017 at 9:38
This is often a PATH problem... Did you try to pass the full path of sed (generally /usr/bin/sed)? — Serge Ballesta
– Serge Ballesta, Commented Jun 1, 2017 at 9:55
definitely not, do it need a full path ? please advise, i am new to Linux — yumi
– yumi, Commented Jun 1, 2017 at 10:01

Vitaliy Moskalyuk · Accepted Answer · 2017-06-01 11:12:41Z

1

In my case worked:

 ProcessBuilder processBuilder = new ProcessBuilder("/bin/bash", "-c", "pwd")
                    .directory(new File("some.directory.path"));
 Process process = processBuilder.start();

Or you can sip using ProcessBuilder and just call

String command = "ping www.google.com";
String[] commandArray = {"/bin/bash", "-c", "pwd"}; 
Runtime.getRuntime().exec(commandArray);

"/bin/bash" 0 means that you are going to exec command in bach

"-c" -defines that next param is command

command - any command like "ping www.google.com" or "./script.sh" that you execute with terminal

you should just place your command instead of "ping www.google.com", but as you haven't specified directory - script will be executed from project directory (you can check it by executing "pwd" command that prints current directory). That is why ProcessBuilder is more preferable, as you can indicate execution directory there (replace "some.directory.path" with your dir).

.directory(new File("path/to/some/dir"));

edited Jun 1, 2017 at 11:12

answered Jun 1, 2017 at 9:46

Vitaliy Moskalyuk

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11 Comments

yumi Over a year ago

so you mean I need to replace the "pwd" with my "sed" ?

yumi Over a year ago

i had tested with a short command like "ping www.yahoo.com" or "grep apple app.log", it's works. When the command become more longer, it's cant call out by using the program

Vitaliy Moskalyuk Over a year ago

I mean that you need to pass all 3 params ("/bin/bash", "-c", command), where command = real command you want to execute in terminal

yumi Over a year ago

I provided in the post, will try out any others longer command

yumi Over a year ago

it's show me this error in my terminal "no suitable method found for exec(String,String,String) " when i pass in all three param

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