pstreeコマンドが実行出来なかった場合対応

pstreeを実行してみよう

pstree
%入力したが実行できず、それで　yum install psmisc -yを入力してインストール
%-yオプションはすべてyesにするという意味になる
%実行例は-yをしなかったので一回yを入力した。

```
[root@ik1-331-25935 subNewDir3]# yum install psmisc
Loaded plugins: fastestmirror, langpacks
base                                                                                                                                             | 3.6 kB  00:00:00
epel/x86_64/metalink                                                                                                                             | 7.8 kB  00:00:00
epel                                                                                                                                             | 4.7 kB  00:00:00
extras                                                                                                                                           | 3.4 kB  00:00:00
updates                                                                                                                                          | 3.4 kB  00:00:00
(1/7): base/7/x86_64/group_gz                                                                                                                    | 156 kB  00:00:01
(2/7): epel/x86_64/group_gz                                                                                                                      | 266 kB  00:00:01
(3/7): extras/7/x86_64/primary_db                                                                                                                | 185 kB  00:00:01
(4/7): epel/x86_64/updateinfo                                                                                                                    | 904 kB  00:00:03
(5/7): updates/7/x86_64/primary_db                                                                                                               | 6.9 MB  00:00:04
(6/7): epel/x86_64/primary_db                                                                                                                    | 6.3 MB  00:00:07
(7/7): base/7/x86_64/primary_db                                                                                                                  | 5.7 MB  00:00:08
Determining fastest mirrors
 * base: ftp.iij.ad.jp
 * epel: mirror01.idc.hinet.net
 * extras: ftp.iij.ad.jp
 * updates: ftp.iij.ad.jp
Resolving Dependencies
--> Running transaction check
---> Package psmisc.x86_64 0:22.20-15.el7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

========================================================================================================================================================================
 Package                                Arch                                   Version                                       Repository                            Size
========================================================================================================================================================================
Installing:
 psmisc                                 x86_64                                 22.20-15.el7                                  base                                 141 k

Transaction Summary
========================================================================================================================================================================
Install  1 Package

Total download size: 141 k
Installed size: 475 k
Is this ok [y/d/N]: y
Downloading packages:
psmisc-22.20-15.el7.x86_64.rpm                                                                                                                   | 141 kB  00:00:00
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
  Installing : psmisc-22.20-15.el7.x86_64                                                                                                                           1/1
  Verifying  : psmisc-22.20-15.el7.x86_64                                                                                                                           1/1

Installed:
  psmisc.x86_64 0:22.20-15.el7

Complete!
```
pstree %インストール後実行結果

```
[root@ik1-331-25935 subNewDir3]# pstree
systemd-+-NetworkManager---2*[{NetworkManager}]
        |-abrt-watch-log
        |-abrtd
        |-2*[agetty]
        |-atd
        |-auditd---{auditd}
        |-chronyd
        |-crond
        |-dbus-daemon
        |-fail2ban-server---2*[{fail2ban-server}]
        |-firewalld---{firewalld}
        |-lsmd
        |-lvmetad
        |-master-+-pickup
        |        `-qmgr
        |-polkitd---5*[{polkitd}]
        |-rngd
        |-rsyslogd---2*[{rsyslogd}]
        |-smartd
        |-sshd---sshd---bash---pstree
        |-systemd-journal
        |-systemd-logind
        |-systemd-udevd
        |-tuned---4*[{tuned}]
        `-wpa_supplicant
```
pstree -p %プロセスID確認コマンドまたは　topコマンド