how to run unix commands from java

Question

I want to execute some Unix commands from the java code.

I want to run logcat command from java code.

I am using the below code to do this:

  Process p = Runtime.getRuntime().exec("logcat -v time -f /mnt/sdcard/abc.txt");

The above code is working perfectly.

The same way I want to run some other Unix commands .

I want to run "WC -l"(read no.of lines in file) command and I want to store it out put in some integer.

Below is the code that I have written for this:

 Process p = Runtime.getRuntime().exec("wc -l /mnt/sdcard/abc.txt");

But it is throwing below exception.

   08-19 05:34:53.457 W/System.err( 1269): java.io.IOException: Error running exec(). Command: [wc, -l, /mnt/sdcard/abc.txt] Working Directory: null Environment: null

   08-19 05:34:53.457 W/System.err( 1269):  at java.lang.ProcessManager.exec(ProcessManager.java:224)

   08-19 05:34:53.457 W/System.err( 1269):  at java.lang.Runtime.exec(Runtime.java:189)

   08-19 05:34:53.457 W/System.err( 1269):  at java.lang.Runtime.exec(Runtime.java:275)

   08-19 05:34:53.457 W/System.err( 1269):  at java.lang.Runtime.exec(Runtime.java:210)

Please help me what's the issue in this..

I have a file "abc.txt" in SD card.

is it possible to execute "WC -l" command from java code of android.

If we can execute Unix commands from java code we can make file operations very easier.

did you read that post: stackoverflow.com/questions/1410741/… — Romain Piel
– Romain Piel, Commented Aug 19, 2011 at 9:43

Emmanuel Devaux · Accepted Answer · 2011-08-19 10:00:40Z

Here the list of the System /bin in android there is no "wc" sorry

am                 check_prereq  dexopt       fsck_msdos    iftop     keystore_cli  mediaserver  netd         ps            rild       service         stagefright     toolbox
applypatch         chmod         df           gdbjithelper  ime       kill          mkdir        netstat      qemud         rm         servicemanager  start           top
applypatch_static  chown         dhcpcd       gdbserver     input     linker        monkey       newfs_msdos  qemu-props    rmdir      setconsole      stop            umount
app_process        cmp           dmesg        getevent      insmod    ln            mount        notify       racoon        rmmod      setprop         surfaceflinger  updater
audioloop          dalvikvm      dnsmasq      getprop       installd  log           mtpd         omx_tests    radiooptions  route      sh              svc             vdc
bmgr               date          dumpstate    gzip          ioctl     logcat        mv           ping         reboot        run-as     showlease       sync            vmstat
bootanimation      dbus-daemon   dumpsys      hd            ionice    logwrapper    nandread     pm           record        schedtest  skia_test       system_server   vold
bugreport          dd            dvz          id            iptables  ls            ndc          pppd         recovery      schedtop   sleep           tc              watchprops
cat                debuggerd     flash_image  ifconfig      keystore  lsmod         netcfg       printenv     renice        sendevent  smd             testid3         wipe

njzk2 · Accepted Answer · 2011-08-19 09:56:32Z

1

wc is not present on android.

dev:~ njzk2$ ./adb shell wc
wc: not found

However, you can consider opening the file and counting the number of lines from there.

answered Aug 19, 2011 at 9:56

njzk2

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Comments

Pestro · Accepted Answer · 2019-03-03 21:38:48Z

0

You can try grep instead.

The following command:

$ wc -l filename

outputs the equivalent to:

$ grep -c '.*' filename

The expression .* means any character except line break zero or more times, which works for lines of every possible size.

Related: https://unix.stackexchange.com/q/25344

PS: You can play with and debug regular expressions at https://regexr.com/

answered Mar 3, 2019 at 21:38

Pestro

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