Linux/UNIX系统编程手册课后习题代码

Chapter 12: System and Process Information ========================================== Exercise 12-1 ------------- **Question** Write a program that lists the porcess ID and command name for all processes being run by the user named in the program's command-line argument. (You may find the userIdFromName() function from Listing 8-1, on page 159, useful.) This can be done by inspecting the Name: and Uid: lines of all of the /proc/PID/status files on the system. Walking through all of the /proc/PID directories on the system requires the use of readdir(3), which is described in Section 18.8. Make sure your porgram correctly handles the possibility that a /proc/PID directory disappears between the time that the porgram determines that the directory exists and the time that it tries to open the corresponding /proc/PID/status file. **Answer** See proclist.c. Example Output: ``` [posborne@pobox-lin:~/Projects/linux-programming-interface-exercises/ch12 git:master] $ ./prog_proclist posborne 22548: prog_proclist 1105: chrome 1115: chrome 1325: chrome 1658: mate-session 1693: ssh-agent 1696: dbus-launch 1697: dbus-daemon 1704: mateconfd-2 1708: mate-keyring-da 1716: mate-settings-d 1720: gvfsd 1722: gvfs-fuse-daemo 1733: gvfs-gdu-volume 1743: gvfs-afc-volume 1746: gvfs-gphoto2-vo 1751: mate-panel 1754: caja 1758: mate-power-mana 1759: deja-dup-monito 1762: zeitgeist-datah 1767: matecomponent-a 1769: mate-bluetooth- 1775: polkit-mate-aut 1776: nm-applet 1787: zeitgeist-daemo 1790: mate-settings-d 1791: gnome-do 1793: mate-settings-d 1798: update-notifier 1805: zeitgeist-fts 1813: applet.py 1820: wnck-applet 1822: pulseaudio 1830: mate-screensave 1833: clock-applet 1835: multiload-apple 1837: notification-ar 1855: gnome-do 2023: cat 2026: gvfsd-trash 2033: gconfd-2 2054: gconf-helper 2085: gvfsd-metadata 2105: chrome 2112: chrome 2113: chrome-sandbox 2114: chrome 2116: nacl_helper_boo 2117: chrome 2153: chrome 2204: chrome 2217: chrome 2316: at-spi-bus-laun 2592: mixer_applet2 2704: chrome 2811: chrome 2835: chrome 2845: chrome 2869: chrome 2892: chrome 2908: chrome 2932: emacs 2936: chrome 2949: chrome 2961: chrome 2968: chrome 2989: chrome 3202: notify-osd 3210: dconf-service 7241: chrome 7833: chrome 10392: eclipse 10463: java 12447: chrome 14552: firefox 14587: plugin-containe 14721: mate-terminal 14727: mate-terminal 14728: bash 19678: marco 19691: chrome 19794: chrome 19898: chrome 19909: chrome 19939: chrome 19960: chrome 19979: chrome 20035: chrome 20107: chrome 20519: chrome 20706: emacsclient 22548: prog_proclist ``` Exercise 12-2 ------------- **Question** Write a program that draws a tree showing the hierarchical parent-child relationships of all processes on the system, going all the way back to init. For each process, the program should display the process ID and the command being executed. The output of the program should be similar to that produced by pstree(1), although it does need not to be as sophisticated. The parent of each process on the system can be found by inspecing the PPid: line of all of the /proc/PID/status files on the system. Be careful to handle the possibilty that a process's parent (and thus its /proc/PID directory) disappears during the scan of all /proc/PID directories. **Answer** See pstree.c. Example output: ``` [posborne@pobox-lin:~/Projects/linux-programming-interface-exercises/ch12 git:master] $ ./prog_pstree kthreadd (pid: 2, ppid: 0) kworker/0 (pid: 23815, ppid: 2) kworker/3 (pid: 23695, ppid: 2) kworker/0 (pid: 23603, ppid: 2) kworker/1 (pid: 23453, ppid: 2) krfcommd (pid: 1054, ppid: 2) flush-8 (pid: 944, ppid: 2) hd-audio1 (pid: 805, ppid: 2) hd-audio0 (pid: 801, ppid: 2) edac-poller (pid: 746, ppid: 2) ext4-dio-unwrit (pid: 312, ppid: 2) jbd2/sdb5-8 (pid: 311, ppid: 2) scsi_eh_5 (pid: 292, ppid: 2) scsi_eh_4 (pid: 290, ppid: 2) firewire (pid: 270, ppid: 2) devfreq_wq (pid: 121, ppid: 2) kworker/u (pid: 92, ppid: 2) kworker/u (pid: 90, ppid: 2) scsi_eh_3 (pid: 88, ppid: 2) scsi_eh_2 (pid: 87, ppid: 2) scsi_eh_1 (pid: 86, ppid: 2) scsi_eh_0 (pid: 85, ppid: 2) kthrotld (pid: 77, ppid: 2) crypto (pid: 69, ppid: 2) ecryptfs-kthrea (pid: 68, ppid: 2) fsnotify_mark (pid: 67, ppid: 2) khugepaged (pid: 66, ppid: 2) ksmd (pid: 65, ppid: 2) kswapd0 (pid: 64, ppid: 2) khungtaskd (pid: 63, ppid: 2) md (pid: 32, ppid: 2) khubd (pid: 31, ppid: 2) ata_sff (pid: 30, ppid: 2) kblockd (pid: 29, ppid: 2) kintegrityd (pid: 28, ppid: 2) bdi-default (pid: 27, ppid: 2) sync_supers (pid: 26, ppid: 2) netns (pid: 24, ppid: 2) kdevtmpfs (pid: 23, ppid: 2) khelper (pid: 22, ppid: 2) cpuset (pid: 21, ppid: 2) watchdog/3 (pid: 20, ppid: 2) ksoftirqd/3 (pid: 19, ppid: 2) kworker/3 (pid: 18, ppid: 2) migration/3 (pid: 17, ppid: 2) watchdog/2 (pid: 16, ppid: 2) ksoftirqd/2 (pid: 15, ppid: 2) migration/2 (pid: 13, ppid: 2) watchdog/1 (pid: 12, ppid: 2) ksoftirqd/1 (pid: 10, ppid: 2) migration/1 (pid: 8, ppid: 2) watchdog/0 (pid: 7, ppid: 2) migration/0 (pid: 6, ppid: 2) ksoftirqd/0 (pid: 3, ppid: 2) init (pid: 1, ppid: 0) mate-terminal (pid: 14721, ppid: 1) mate-terminal (pid: 14727, ppid: 14721) firefox (pid: 14552, ppid: 1) eclipse (pid: 10392, ppid: 1) dconf-service (pid: 3210, ppid: 1) notify-osd (pid: 3202, ppid: 1) emacs (pid: 2932, ppid: 1) mixer_applet2 (pid: 2592, ppid: 1) hald (pid: 2454, ppid: 1) at-spi-bus-laun (pid: 2316, ppid: 1) chrome (pid: 2105, ppid: 1) chrome-sandbox (pid: 2113, ppid: 2105) chrome (pid: 2112, ppid: 2105) system-service- (pid: 2087, ppid: 1) gvfsd-metadata (pid: 2085, ppid: 1) SystemToolsBack (pid: 2070, ppid: 1) system-tools-ba (pid: 2044, ppid: 1) gconfd-2 (pid: 2033, ppid: 1) gvfsd-trash (pid: 2026, ppid: 1) notification-ar (pid: 1837, ppid: 1) multiload-apple (pid: 1835, ppid: 1) clock-applet (pid: 1833, ppid: 1) mate-screensave (pid: 1830, ppid: 1) upowerd (pid: 1829, ppid: 1) rtkit-daemon (pid: 1824, ppid: 1) pulseaudio (pid: 1822, ppid: 1) wnck-applet (pid: 1820, ppid: 1) zeitgeist-fts (pid: 1805, ppid: 1) zeitgeist-daemo (pid: 1787, ppid: 1) matecomponent-a (pid: 1767, ppid: 1) gvfs-gphoto2-vo (pid: 1746, ppid: 1) gvfs-afc-volume (pid: 1743, ppid: 1) udisks-daemon (pid: 1735, ppid: 1) gvfs-gdu-volume (pid: 1733, ppid: 1) gvfs-fuse-daemo (pid: 1722, ppid: 1) gvfsd (pid: 1720, ppid: 1) mate-keyring-da (pid: 1708, ppid: 1) mateconfd-2 (pid: 1704, ppid: 1) dbus-daemon (pid: 1697, ppid: 1) dbus-launch (pid: 1696, ppid: 1) console-kit-dae (pid: 1583, ppid: 1) accounts-daemon (pid: 1560, ppid: 1) getty (pid: 1515, ppid: 1) hddtemp (pid: 1280, ppid: 1) whoopsie (pid: 1132, ppid: 1) polkitd (pid: 1118, ppid: 1) atd (pid: 1114, ppid: 1) irqbalance (pid: 1112, ppid: 1) cron (pid: 1111, ppid: 1) lightdm (pid: 1102, ppid: 1) lightdm (pid: 22010, ppid: 1102) lightdm (pid: 21029, ppid: 1102) lightdm (pid: 1555, ppid: 1102) Xorg (pid: 1146, ppid: 1102) avahi-daemon (pid: 1100, ppid: 1) acpid (pid: 1099, ppid: 1) getty (pid: 1094, ppid: 1) getty (pid: 1092, ppid: 1) getty (pid: 1091, ppid: 1) colord (pid: 1089, ppid: 1) getty (pid: 1075, ppid: 1) NetworkManager (pid: 1070, ppid: 1) dhclient (pid: 1148, ppid: 1070) getty (pid: 1061, ppid: 1) bluetoothd (pid: 1039, ppid: 1) cupsd (pid: 1023, ppid: 1) modem-manager (pid: 996, ppid: 1) dbus-daemon (pid: 970, ppid: 1) rsyslogd (pid: 923, ppid: 1) mount.ntfs (pid: 870, ppid: 1) mount.ntfs (pid: 833, ppid: 1) upstart-socket- (pid: 824, ppid: 1) udevd (pid: 515, ppid: 1) udevd (pid: 1499, ppid: 515) upstart-udev-br (pid: 50