linux bg and fg commands

linux bg and fg commands

Under linux, if we want a task or program to be executed in the background, we can use &. In fact, linux also provides commands for other task scheduling.

  1. bg: change a command suspended in the background to continue execution; [background background background]
  2. fg: transfer the command in the background to the foreground and continue to run, [foreground: foreground, important position]
  3. jobs: check how many commands are currently running in the background
  4. ctrl + z: you can put a command being executed in the foreground into the background and pause it
  5. nohup command: run the command without hanging up. nohup means no hang up.


nohup Command [ Arg ... ] [ & ]

Description: the nohup Command runs the Command specified by the Command parameter and any related Arg parameter, ignoring all hangup signals. After logging off, use the nohup Command to run the program in the background. To run the nohup Command in the background, add & (the symbol for "and") to the end of the Command

Let's take a look at the actual operation example and start a clock program:

After ctrl+z, the output is:
This uses pidof xclock to check whether the process number still exists, indicating that the program is suspended in the background

Execute BG% 1 to see the program continue
A more obvious example shows the difference between bg and fg: Firefox & the difference between symbols


If you are running a process and you think it will not end when you exit the account, you can use the nohup command. This command can continue to run the corresponding process after you exit your account. The general form of this command is:

nohup conmmand &

If you submit a job using the nohup command, by default, all the output of the job is redirected to a named nohup Out, unless otherwise specified:

nohup command > myout.file 2>&1 

In the above example, the output is redirected to myout File

Full name of linux command

For people who use Linux system, common commands, such as cd/ls/ll /, will be knocked out, but this is only an abbreviation. I think understanding the full name of these instructions is more helpful for us to understand and remember these instructions.

pwd:print work directory Print the current directory and display the absolute path of the current working directory
ps: process status(Process status, similar to windows Task manager for) Common parameters:-auxf
ps -auxf Show process status
df: disk free Its function is to display the number of available disk space and space node information. In other words, report how much free space is left in any installed device or directory.
du: Disk usage
rpm: Namely RedHat Package Management,yes RedHat One of the inventions of
rmdir: Remove Directory(Delete directory)
rm: Remove(Delete directory or file)
cat: concatenate chain
cat file1 file2>>file3 Combine the contents of document 1 and document 2 into file3 in
insmod: install module,Load module
ln -s : link -soft Creating a soft link is equivalent to creating a shortcut
mkdir: Make Directory(Create directory)
touch  Create a file
man: Manual
su: Swith user(Switch users)
cd: Change directory
ls: List files
ps: Process Status
rmdir: Remove directory
mkfs: Make file system
fsck: File system check
uname: Unix name
lsmod: List modules
mv: Move file  Duplicate name file
rm: Remove file  Delete file
cp: Copy file Copy, of course, can be followed by some parameters. See the specific use of this command
ln: Link files 
fg: Foreground
bg: Background
chown: Change owner
chgrp: Change group
chmod: Change mode
umount: Unmount
tar: Tape archive (Tape Archive)
ldd: List dynamic dependencies
.a(Extension a): Archive,static library
.so(Extension so): Shared object,dynamically linked library
.o(Extension o): Object file,complied result of C/C++ source file
dpkg: Debian package manager
apt: Advanced package tool(Debian Or based on Debian Some are available in the release of Linux Command abbreviation)
bin = Binaries (Binary file)
apache = "a patchy" server
apt = Advanced Packaging Tool
ar = archiver
as = assembler
awk = "Aho Weiberger and Kernighan"The first letter of the last name of the three authors
bash = Bourne Again SHell
chsh = Change Shell
cmp = compare
cobra = Common Object Request BrokerArchitecture
comm = common
cpio = CoPy In and Out
cpp = C Pre Processor
ed = editor
egrep = Extended GREP
elf = Extensible Linking Format
elm = ELectronic Mail
emacs = Editor MACroS
eval = EVALuate
fd = file descriptors
fg = ForeGround
fgrep = Fixed GREP
fmt = format
fsck = File System ChecK
fstab = FileSystem TABle
fvwm = F*** Virtual Window Manager
gawk = GNU AWK
gpg = GNU Privacy Guard
groff = GNU troff
hal = Hardware Abstraction Layer
joe = Joe's Own Editor
ksh = Korn SHell
lame = Lame Ain't an MP3 Encoder
lex = LEXical analyser
lisp = LISt Processing = Lots of IrritatingSuperfluous Parentheses
ls = list
lsof = LiSt Open Files

Keywords: Linux Operation & Maintenance server

Added by radi8 on Thu, 10 Mar 2022 18:38:38 +0200