如何使“ top”命令在Java运行时中工作，以返回进程列表以及每个进程消耗的资源量？

Question

This is kind of a newb question, so please forgive me, I am a newb. Before posting I have checked all x billion pages on the Internet and there is not answer to my specific question. Okay not really, but it's been a good four hours of desk punching so I feel it is a good time to defer to the vast and seemingly all encompassing knowledge of the SE user base. So, without further ado... here is my question.

As stated above, I am working with bash (OSX) and Java, and trying to get a script to run via process-builder (and/or Java runtime) IN THE EXACT SAME WAY that it would run by running it in the shell alone.

for example, if I write a shell script (.sh) containg the code:

"#!/bin/bash"
"top > /Users/NN2/Desktop/test.txt"

the file runs fine, and the expected output is created. However, if I do the following:

(excluded try/catch in example only)
ProcessBuilder builder = new ProcessBuilder(new String[]{"/bin/sh","/Users/NN2/Desktop/configure.sh"});

or

Runtime.getRuntime().exec("/Users/NN2/Desktop/configure.sh");

Either nothing happens, or a truncated version of the original appears, which does not include the #MREG info. In addition to the above two examples, I have tried what seems like an exhaustive list of other variations and it is always the same, either truncated or nothing. Furthermore, this problem seems to only be with the "top" command, as most other commands I have tried do indeed work (ex: ls, ef aux, etc..).

I have read that other people have had permission issues with the top command from within Java, however, I have used the chmod command on several other installations so this is likely not the cause of the problem either. However, if it is, then it is surely due to not knowing which files need to be chmod'ed.

Also, if there is any other way to find the information I need besides what I am doing please do tell. In the end, I just want to be able to use java to check what process are running on my computer, and how much memory they have used (to tell when a program has finished loading) before I do other things. Different file sizes open at different durations, so thread.sleep command is a work-around that I do not wish to use.

Thank you

Answer 1

I tired something like...

ProcessBuilder pb = new ProcessBuilder("top", "-l", "1");
pb.redirectError();
try {
    Process p = pb.start();
    InputStream is = p.getInputStream();
    int value = -1;
    while ((value = is.read()) != -1) {
        System.out.print(((char)value));
    }
    int exitCode = p.waitFor();
    System.out.println("Top exited with " + exitCode);
} catch (IOException exp) {
    exp.printStackTrace();
} catch (InterruptedException ex) {
    Logger.getLogger(JavaApplication256.class.getName()).log(Level.SEVERE, null, ex);
}

And it output something like...

PID    COMMAND          %CPU TIME     #TH   #WQ #PORTS MEM    PURG   CMPRS  PGRP  PPID  STATE    BOOSTS      %CPU_ME %CPU_OTHRS UID FAULTS     COW        MSGSENT    MSGRECV    SYSBSD      SYSMACH   CSW         PAGEINS  IDLEW     POWER USER            #MREGS RPRVT VPRVT VSIZE KPRVT KSHRD
96500  USBAgent         0.0  00:00.02 2     1   34+    380K+  0B     720K+  96500 1     sleeping *0[1+]      0.00000 0.00000    501 2044+      135+       151+       55+        786+        310+      287+        0        9         0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
96499  smd              0.0  00:00.01 2     1   19+    8192B+ 0B     808K+  96499 1     sleeping *0[1+]      0.00000 0.00000    0   1066+      110+       73+        30+        430+        158+      146+        0        3         0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
84070  DiskUnmountWatch 0.0  00:00.02 2     1   25+    8192B+ 0B     852K+  84070 1     sleeping  0[0]       0.00000 0.00000    501 1290+      115+       201+       95+        1840+       313+      367+        0        5         0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83951  ath              0.0  00:11.89 6     0   52+    4104K+ 0B     24M+   83850 83850 sleeping *0[14+]     0.00000 0.00000    501 14309+     152+       7429+      3385+      246813+     40467+    104382+     47+      821       0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83930  com.apple.iTunes 0.0  00:26.91 2     1   45+    9736K+ 0B     76M+   83930 1     sleeping *0[6+]      0.00000 0.00000    501 101584+    149+       742302+    278377+    1094603+    464425+   387242+     49+      15        0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83911  AppleMobileDevic 0.0  00:00.14 3     0   47+    24K+   0B     4500K+ 83850 83850 sleeping *0[10+]     0.00000 0.00000    501 3416+      202+       677+       298+       3344+       1005+     1292+       71+      21        0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83907  com.apple.MediaL 0.0  02:04.68 2     0   85+    60M+   0B     75M+   83907 1     sleeping *0[41+]     0.00000 0.00000    501 215329+    1028+      763618+    373231+    3447492+    1274798+  1276787+    11429+   128       0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83866  ath              0.0  00:06.18 4     0   40+    2120K+ 0B     13M+   83850 83850 sleeping *0[10+]     0.00000 0.00000    501 8056+      152+       5462+      2504+      136223+     31146+    37582+      3+       604       0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
83854  com.apple.BKAgen 0.0  00:00.04 2     1   42+    20K+   0B     1464K+ 83854 1     sleeping *0[2+]      0.00000 0.00000    501 2775+      171+       218+       93+        878+        469+      459+        37+      9         0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
.
.
.
29     thermald         0.0  00:00.60 2     0   31+    576K+  0B     544K+  29    1     sleeping *0[1+]      0.00000 0.00000    0   8021+      139+       12033+     6007+      28656+      16489+    12726+      52+      1009      0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
27     fseventsd        0.0  06:03.81 9     0   219+   8384K+ 0B     4168K+ 27    1     sleeping *0[1+]      0.00000 0.00000    0   1324890+   88+        673284+    16997+     20680415+   3283315+  5048419+    18+      550698    0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
26     kextd            0.0  00:49.92 2     0   58+    4628K+ 0B     13M+   26    1     sleeping *0[1+]      0.00000 0.00000    0   106864+    563+       10668+     6440+      431944+     36727+    136669+     2775+    245       0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
25     com.bombich.ccch 0.0  00:00.87 2     0   66+    1108K+ 0B     3068K+ 25    1     sleeping *0[1+]      0.00000 0.00000    0   10385+     221+       8129+      5704+      25753+      27131+    16864+      243+     282       0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
24     EyeConnect       0.0  01:55.37 12    0   61+    6964K+ 0B     4556K+ 24    1     sleeping *0[1+]      0.00000 0.00000    0   12222+     260+       1747+      1180+      3097895+    2482+     1264730+    892+     466746    0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
22     UserEventAgent   0.0  03:08.20 4     1   1439+  6220K+ 0B     2336K+ 22    1     sleeping *0[1+]      0.00000 0.00000    0   1136602+   295+       3259840+   1922426+   8525137+    6153879+  5940157+    1529+    141344    0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
21     syslogd          0.0  01:07.95 7     6   183+   956K+  0B     256K+  21    1     stuck    *0[116596+] 0.00000 0.00000    0   304083+    72+        1247136+   424254+    4546991+    1774131+  1223614+    10+      22760     0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
1      launchd          0.0  22:36.73 6     4   3547+  9800K+ 0B     3524K+ 1     0     sleeping  0[0]       0.00000 0.00000    0   158340+    6059+      18904581+  9244535+   30306022+   32624561+ 12693124+   1172+    42752     0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
0      kernel_task      0.0  20:23:16 100/4 0   2+     686M+  0B     0B     0     0     running   0[0]       0.00000 0.00000    0   25398+     0          258323633+ 231211103+ 0           0         2322888249+ 0        708699634 0.0   ...             N/A    N/A   N/A   N/A   N/A   N/A  
Top exited with 0

Now, obviously, you'll need to parse the individual lines to get meaningful information, but no more then you would have to by reading the output file...