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Java Forum / General / March 2006Runtime and process picking up unwanted char's
Hi all, I was looking at a problem at comp.os.linux.misc - trying to put 'pgrep' thru 'wc -w' . Allow the code below to explain: package org.client; import java.util.*; import java.io.*; public class Pgrep { public static void main(String[] args) { try { // String[] cmd = new String[]{"sh", "-c", "/usr/bin/pgrep -f konqueror | /usr/bin/wc -w" // String[] cmd = new String[]{"sh", "-c", "/usr/bin/pgrep -f konqueror" String[] cmd = new String[]{"sh", "-c", "/usr/bin/pgrep -f konqueror | od -c" }; System.out.println(cmd[0] + " " + cmd[1] + " " + cmd[2]); Runtime rt = Runtime.getRuntime(); Process proc = rt.exec(cmd); // put a BufferedReader on the ls output InputStream inputstream = proc.getInputStream(); InputStreamReader inputstreamreader = new InputStreamReader(inputstream); BufferedReader bufferedreader = new BufferedReader(inputstreamreader); // read the ls output String line; while ((line = bufferedreader.readLine()) != null) { System.out.println(line); } // check for failure if (proc.waitFor() != 0) { System.err.println("exit value = " + proc.exitValue()); } } catch (Exception ex) { ex.printStackTrace(); } } } >From the shell I have: /home/iksrazal/ahelp> ps -ef | grep [k]onqueror iksrazal 23848 7744 0 Mar14 ? 00:01:05 konqueror [kdeinit] konqueror --silent iksrazal 29474 7744 0 Mar14 ? 00:00:00 kio_file [kdeinit] kio_file file /tmp/ksocket-iksrazal/klauncherkxpgOb.slave-socket /tmp/ksocket-iksrazal/konquerorRuDO7b.slave-socket /home/iksrazal/ahelp> /usr/bin/pgrep -f konqueror | wc -w 2 Running from the above program - with the command above running 'wc -w' I get 3. Running the version with 'od -c' I get: [echo] running grep [java] sh -c /usr/bin/pgrep -f konqueror | od -c [java] 0000000 2 3 8 4 8 \n 2 9 4 7 4 \n 1 7 8 2 [java] 0000020 7 \n [java] 0000022 With the content after '23848' and '29474' changing with every invokation. Any ideas? Robert http://www.braziloutsource.com/ > Hi all, > > I was looking at a problem at comp.os.linux.misc - trying to put > 'pgrep' thru 'wc -w' . Allow the code below to explain: It just occurred to me. Might the java program itself be picking up the 'pgrep' process looking for 'konqueror' ? :-) . Robert http://www.braziloutsource.com/index.html > It just occurred to me. Might the java program itself be picking up > the 'pgrep' process looking for 'konqueror' ? :-) . More likely your grep/pgrep is detecting itself due to the matching argument. Is there a Java issue here? /gordon  Signature[ do not email me copies of your followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e > > It just occurred to me. Might the java program itself be picking up > > the 'pgrep' process looking for 'konqueror' ? :-) . [quoted text clipped - 5 lines] > > /gordon The java issue is that the pgrep command as written returns 3 with java while the same command in the shell returns 2. See the OP if interested. While grep detects itself by default, using [] with it as my example shows it does not. Neither does pgrep. Robert > The java issue is that the pgrep command as written returns 3 with > java while the same command in the shell returns 2. See the OP if > interested. While grep detects itself by default, using [] with it > as my example shows it does not. Neither does pgrep. The original post shows that [] was *not* being used in the command passed to Runtime.exec(), only in the shell examples. /gordon Signature[ do not email me copies of your followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e > > The java issue is that the pgrep command as written returns 3 with > > java while the same command in the shell returns 2. See the OP if [quoted text clipped - 5 lines] > > /gordon I know you're trying to help - and in fact you have helped me in the past. What I meant by 'Neither does pgrep' - and I should have been more clear - is that pgrep _does not_ in any way list itself in the results as does the default behavior or grep. /home/iksrazal> ps -ef | grep konqueror iksrazal 23848 7744 0 Mar14 ? 00:01:08 konqueror [kdeinit] konqueror --silent iksrazal 18905 1 0 Mar15 ? 00:01:41 konqueror [kdeinit] konqueror -mimetype text/html http://fortaleza.techdays.soujava.org.br iksrazal 29806 7744 0 10:04 ? 00:00:00 kio_file [kdeinit] kio_file file /tmp/ksocket-iksrazal/klauncherkxpgOb.slave-socket /tmp/ksocket-iksrazal/konquerorlPtb2b.slave-socket iksrazal 31765 10406 0 11:55 pts/2 00:00:00 grep konqueror [linux(iksrazal)] /home/iksrazal> ps -ef | grep [k]onqueror iksrazal 23848 7744 0 Mar14 ? 00:01:08 konqueror [kdeinit] konqueror --silent iksrazal 18905 1 0 Mar15 ? 00:01:41 konqueror [kdeinit] konqueror -mimetype text/html http://fortaleza.techdays.soujava.org.br iksrazal 29806 7744 0 10:04 ? 00:00:00 kio_file [kdeinit] kio_file file /tmp/ksocket-iksrazal/klauncherkxpgOb.slave-socket /tmp/ksocket-iksrazal/konquerorlPtb2b.slave-socket [linux(iksrazal)] /home/iksrazal> pgrep konqueror 23848 18905 (java program, all three 'cmd' options shown in OP code) [echo] running grep [java] sh -c /usr/bin/pgrep -f konqueror | od -c [java] 0000000 2 3 8 4 8 \n 1 8 9 0 5 \n 2 9 8 0 [java] 0000020 6 \n 3 2 0 1 8 \n [java] 0000030 Where is ' 3 2 0 1 8' comming from? [echo] running grep [java] sh -c /usr/bin/pgrep -f konqueror | /usr/bin/wc -w [java] 4 [echo] running grep [java] sh -c /usr/bin/pgrep -f konqueror [java] 23848 [java] 18905 [java] 29806 Robert > (java program, all three 'cmd' options shown in OP code) > [quoted text clipped - 6 lines] > > Where is ' 3 2 0 1 8' comming from? Try this in a command shell: [linux]$ sh -c "/usr/bin/pgrep -fl konqueror | cat" ("cat" output is easier to read than od -c for this) You will find that pgrep is matching the sh process (with all of its arguments). It seems that pgrep is smart enough to remove itself from the list, and even sh when you don't use any redirection. However the redirection and extra command throw it off. Specifing -l helps you see which processes are being reported. The extra process is this one: 32018 sh -c /usr/bin/pgrep -fl konqueror | cat /gordon Signature[ do not email me copies of your followups ] g o r d o n + n e w s @ b a l d e r 1 3 . s e > > Where is ' 3 2 0 1 8' comming from? > [quoted text clipped - 13 lines] > > /gordon That explains it! Thanks Gordon, Robert http://www.braziloutsource.com/ Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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