"Brother's Linux Private Dishes" study notes (2)--bash features

Bash and its features:

　　The most recent program from the user is Shell,shell is the shell meaning, itself is an executable program. The shell in its broadest sense consists of two types of GUI and CLI.

Gui:gnome,kde,xface

Cli:sh,csh,ksh,bash,tcsh,zsh

When there are multiple users logged in, there will be multiple processes that are irrelevant to each other, because for each process it only considers itself and the kernel to exist on the current host. But there is only one shell program. Linux allows a user account to log on multiple times.

A process is a copy of a program, a process that is an instance of the execution of a program, has a life cycle, and is managed by the kernel.

User work environment, many users, although the use of shell programs, but the user's working environment settings can be different, but by default, except the administrator, is the same.

Shell, child shell. You can start a child shell in a shell. This relationship can be seen through the Pstree command below, and you can use the Exit command if you exit to the previous layer of bash. When you get back to the top level, you will be logged out.

[[Email protected] ~]$ Bash[[email protected]~]$ Pstreeinit-+-networkmanager-+-dhclient| `-{NetworkManager}|-ABRTD|-Acpid|-ATD|-AUDITD---{AUDITD}|-automount---4*[{automount}]|-bonobo-activati---{bonobo-Activat}|-Certmonger|-clock-applets|-console-kit-dae--- the*[{console-kit-da}] |-Crond|-CUPSD|-2*[dbus-daemon---{dbus-Daemon}] |-2*[dbus-Launch]|-devkit-power-da|-gconf-im-Settin|-gconfd-2|-gdm-binary-+-gdm-simple-slav-+-Xorg|                 | |-gdm-session-wor-+-gnome-session-+-abrt-applets|                 |                 |               | |-bluetooth-Apple|                 |                 |               | |-evolution-Alarm|                 |                 |               | |-gdu-Notificatio|                 |                 |               | |-gnome-Panel|                 |                 |               | |-gnome-power-Mans|                 |                 |               | |-gnome-volume-Co|                 |                 |               | |-gpk-update-icon|                 |                 |               | |-metacity|                 |                 |               | |-Nautilus|                 |                 |               | |-nm-applets|                 |                 |               | |-polkit-gnome-au|                 |                 |               | |-python|                 |                 |               | |-Restorecond|                 |                 |               | '-{gnome-Session}|                 |                 | '-{gdm-session-wo}|                 | '-{gdm-simple-SLA}| '-{gdm-binary}|-gdm-user-Switch|-gnome-keyring-d---2*[{gnome-keyring-}]     |-gnome-Screensav|-gnome-settings----{gnome-Settings}|-Gnote|-gvfs-afc-volume---{gvfs-afc-Volum}|-gvfs-gdu-Volume|-gvfs-gphoto2-Vo|-GVFSD|-gvfsd-Burn|-gvfsd-Computer|-gvfsd-metadata|-gvfsd-Trash|-hald-+-hald-runner-+-hald-addon-ACPI|             | '-hald-addon-Inpu| `-{Hald}|-ibus-X11|-im-settings-dae-+-ibus-daemon-+-ibus-engine-Pin|             | |-ibus-gconf|             | |-python|             | '-{ibus-Daemon}| '-{im-settings-da}|-Login---bash---su---Bash|-master-+-Pickup| `-Qmgr|-4*[Mingetty]|-modem-Manager|-notification-ar|-POLKITD|-pulseaudio-+-gconf-Helper| `-2*[{PulseAudio}]|-rpc.statd|-Rpcbind|-RSYSLOGD---3*[{RSYSLOGD}]|-rtkit-daemon---2*[{rtkit-Daemon}] |-seahorse-Daemon|-sshd---sshd---sshd---bash---bash---pstree|-Trashapplet|-UDEVD---2*[UDEVD]|-udisks-daemon-+-udisks-Daemon| '-{udisks-Daemon}|-wnck-Applet '-Wpa_supplicant[[email protected]~]$ Bash[[email protected]~]$ pstree Init-+-networkmanager-+-dhclient| `-{NetworkManager}|-ABRTD|-Acpid|-ATD|-AUDITD---{AUDITD}|-automount---4*[{automount}]|-bonobo-activati---{bonobo-Activat}|-Certmonger|-clock-applets|-console-kit-dae--- the*[{console-kit-da}] |-Crond|-CUPSD|-2*[dbus-daemon---{dbus-Daemon}] |-2*[dbus-Launch]|-devkit-power-da|-gconf-im-Settin|-gconfd-2|-gdm-binary-+-gdm-simple-slav-+-Xorg|                 | |-gdm-session-wor-+-gnome-session-+-abrt-applets|                 |                 |               | |-bluetooth-Apple|                 |                 |               | |-evolution-Alarm|                 |                 |               | |-gdu-Notificatio|                 |                 |               | |-gnome-Panel|                 |                 |               | |-gnome-power-Mans|                 |                 |               | |-gnome-volume-Co|                 |                 |               | |-gpk-update-icon|                 |                 |               | |-metacity|                 |                 |               | |-Nautilus|                 |                 |               | |-nm-applets|                 |                 |               | |-polkit-gnome-au|                 |                 |               | |-python|                 |                 |               | |-Restorecond|                 |                 |               | '-{gnome-Session}|                 |                 | '-{gdm-session-wo}|                 | '-{gdm-simple-SLA}| '-{gdm-binary}|-gdm-user-Switch|-gnome-keyring-d---2*[{gnome-keyring-}]     |-gnome-Screensav|-gnome-settings----{gnome-Settings}|-Gnote|-gvfs-afc-volume---{gvfs-afc-Volum}|-gvfs-gdu-Volume|-gvfs-gphoto2-Vo|-GVFSD|-gvfsd-Burn|-gvfsd-Computer|-gvfsd-metadata|-gvfsd-Trash|-hald-+-hald-runner-+-hald-addon-ACPI|             | '-hald-addon-Inpu| `-{Hald}|-ibus-X11|-im-settings-dae-+-ibus-daemon-+-ibus-engine-Pin|             | |-ibus-gconf|             | |-python|             | '-{ibus-Daemon}| '-{im-settings-da}|-Login---bash---su---Bash|-master-+-Pickup| `-Qmgr|-4*[Mingetty]|-modem-Manager|-notification-ar|-POLKITD|-pulseaudio-+-gconf-Helper| `-2*[{PulseAudio}]|-rpc.statd|-Rpcbind|-RSYSLOGD---3*[{RSYSLOGD}]|-rtkit-daemon---2*[{rtkit-Daemon}] |-seahorse-Daemon|-sshd---sshd---sshd---bash---bash---bash---pstree|-Trashapplet|-UDEVD---2*[UDEVD]|-udisks-daemon-+-udisks-Daemon| '-{udisks-Daemon}|-wnck-Applet '-wpa_supplicant

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