Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
72 Cards in this Set
- Front
- Back
|
Shell File Order
|
/etc/profile .bash_profile .bashrc /etc/bashrc
|
|
|
Nonlogin shells
|
/etc/bashrc, .bashrc
|
|
|
bash
|
knows what a function is
|
|
|
Path can go anywhere
|
True
|
|
|
Set Path
|
PATH=$PATH:$HOME:/whatever
|
|
|
.(Dot) or source
|
will run a file
|
|
|
()
|
Subshell
|
|
|
$()
|
Command substitution
|
|
|
(())
|
Arithmetic evauluation used when the value includes an equal sign.
|
|
|
$(())
|
Arithmetic expansion not for use with an equal sign.
|
|
|
[]
|
test command
|
|
|
[[]]
|
conditional expression adds string comparisons.
|
|
|
File descriptors
|
the place a program sends its output too and gets its input from.
|
|
|
0
|
Standard input
|
|
|
1
|
standard output
|
|
|
2
|
standard error
|
|
|
>
|
shorthand for 1>
|
|
|
<
|
shorthand for 0<
|
|
|
< filename
|
redirects standard input from filename
|
|
|
> filename
|
redirects standard output to filename. unless filename exists and no clobbber is set. If its not set it creates the file.
|
|
|
>| filename
|
redirects standard output even if no clobber is set and the file exists.
|
|
|
>>
|
redirects and appends standard output.unless filename exists and no clobber is set.
|
|
|
<&m
|
Duplicates standard from file descriptor m
|
|
|
[n]>&m
|
Duplicates standard output or file descriptor n if specified from the file descriptor m?
|
|
|
[n]<&-
|
closes standard input or file descriptor n if specified
|
|
|
[n]>&-
|
Closes standard output or file descriptor n if specified.
|
|
|
#!
|
Specifies a shell
|
|
|
#
|
begins a comment
|
|
|
fork
|
to create a process
|
|
|
exec
|
execute the command
|
|
|
;
|
separates commands
|
|
|
You do not need
|
whitespace
|
|
|
\
|
continues a command on the next line
|
|
|
&
|
backgrounds a process
|
|
|
( )
|
groups commands.
|
|
|
jobs
|
lists jobs
|
|
|
fg
|
brings a job to the foreground can also use a %
|
|
|
bg
|
sends a job to the background
|
|
|
control d
|
end of file
|
|
|
dirs
|
displays the contents of the directory stack
|
|
|
pushd
|
pushes a directory to the stack
|
|
|
popd
|
pops a directory off the stack.
|
|
|
unset
|
removes a variable
|
|
|
readonly
|
makes the value of a variable permanent
|
|
|
declare and typeset
|
set attributes and values for shell variables
|
|
|
declare -a
|
declares a variable as an array
|
|
|
declare -f
|
declares a variables to be a function name
|
|
|
declare -i
|
declares a variable to be of type integer
|
|
|
declare -r
|
makes a variable readonly
|
|
|
declare -x
|
exports a variable
|
|
|
~
|
home
|
|
|
mail
|
usually stored in /var/spool/mail/name
|
|
|
PS1
|
primary user prompt
|
|
|
$
|
prompt / user
|
|
|
#
|
root
|
|
|
PS2
|
User prompt ( Secondary )
|
|
|
PS3
|
Menu prompt
|
|
|
PS4
|
Debugging prompt
|
|
|
IFS
|
Internal Field seperator, seperates input fields
|
|
|
fc
|
displays edis and reexecutes commands.
|
|
|
fc-l
|
displays the 16 most recent commands.
|
|
|
!
|
starts a history event
|
|
|
!!
|
the previous command
|
|
|
!string
|
most recent command that started with that sting
|
|
|
!#
|
current command
|
|
|
Alias
|
a short name that the shell translates into a longer name or complex command.
|
|
|
"" "" quotes
|
litteral
|
|
|
' '
|
non litteral
|
|
|
set -o noclobber
|
turns on
|
|
|
set +o noclobber
|
turns off
|
|
|
0 =
|
True
|
|
|
1 =
|
False
|
