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- Best Bash Prompts
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Jun 04, 2019 Apple is moving away from the bash shell on macOS. The new macOS Catalina update will include zsh as the default shell, and older macOS versions can also move to the new shell too. Nov 05, 2014 How to Prompt for User Input in Linux shell script Written by Rahul, Updated on November 5, 2014. Command: # read var # read -s “Waiting for input: ” var. Uses: read command is used for getting user input in a Linux shell script.p switch with read command is used.
Default bash command line prompt on many Linux systems is quite minimal. Aswe will see in this article, it can be easily changed by modifying bash
PS{n}
variables, so to include information such as display time,load, number of users using the system, uptime and more.In this tutorial you will learn:
- What are PS1 and PS2 shell variables
- How to create custom shell prompts
- What are the characters we can use to customize a shell prompt
Software Requirements and Conventions Used
Category | Requirements, Conventions or Software Version Used |
---|---|
System | Distribution-independent |
Software | No special software is needed to follow this tutorial |
Other | Minimal knowledge of the Bash shell |
Conventions | # - requires given linux commands to be executed with rootprivileges either directly as a root user or by use of sudo command$ - requires given linux commands to be executed as aregular non-privileged user |
Bash prompt variables
As anything else in the Linux system also bash prompt can be customized. Wecan accomplish the task by changing the values of bash
PS1
,PS2
, PS3
, PS4
variables. To keep thethings simple, this article will be concerned just with the first two. Use echocommand to see their values:Subscribe to Linux Career NEWSLETTER and receive latest Linux news, jobs, career advice and tutorials.
Bash PS1 prompt variable
PS1
is a primary prompt variable. Currently it holdsu@h:w$
special bash characters. This is the defaultstructure of the bash prompt on many Linux systems and is displayed every timeyou log in using a terminal. Please see the following section 'Bash promptspecial characters' for explanation of u
, h
,w
and $
symbols. Here is a classical bash promptwith default settings:Bash PS2 prompt variable
PS2
bash shell variable is a secondary prompt. This prompt isdisplayed if the shell waits for a user input, for example you forget to insertsecond quotation.Bash prompt special characters
Bash prompt can be customized by using special characters. Here is a quickoverview of the most used characters and their meaning:
Bash special character | Bash special character explanation | Bash special character | Bash special character explanation |
---|---|---|---|
a | an ASCII bell character (07) | d | the date in 'Weekday Month Date' format (e.g., 'Tue May 26') |
] | end a sequence of non-printing characters | e | an ASCII escape character (033) |
h | the hostname up to the first `.' | H | the hostname |
j | the number of jobs currently managed by the shell | l | the basename of the shell's terminal device name |
n | newline | r | carriage return |
s | the name of the shell, the basename of $0 (the portion following the finalslash) | t | the current time in 24-hour HH:MM:SS format |
T | the current time in 12-hour HH:MM:SS format | @ | the current time in 12-hour am/pm format |
A | the current time in 24-hour HH:MM format | u | the username of the current user |
v | the version of bash (e.g., 2.00) | V | the release of bash, version + patchelvel (e.g., 2.00.0) |
w | the current working directory | W | the basename of the current working directory |
! | the history number of this command | # | the command number of this command |
$ | if the effective UID is 0, a #, otherwise a $ | nnn | the character corresponding to the octal number nnn |
a backslash | [ | begin a sequence of non-printing characters, which could be used to embed aterminal control sequence into the prompt | |
D{format} | the format is passed to strftime(3) and the result is insertedinto the prompt string; an empty format results in a locale-specific timerepresentation. The braces are required |
Bash prompt customization
After user logins into the system, user environment variables are initializedfrom various files:
- /etc/profile or /etc/bashrc (system wide)
- ~/.bash_profile , ~/.bash_login , ~/.profile , ~/.bashrc or ~/.bash_logout (user)
It is important to know that all users environment variable have a life timeequal to the terminal session. When the terminal session is closed the user'svariables including bash shell variables defined during a terminal session areemptied and a again redefined when new terminal session is created either vialogo in shell or interactive shell. Lets define two variables to prove thisstatement.
Best Bash Prompts
Permanent bash variable definition
First, we will define a permanent variable in one of the bash initializationfiles,
~/.bash_profile
, then we will define a temporary variable inthe shell prompt. Let's define permanent user variable:What happened here, is that user 'prompt' modified its own .bash_profileinitialization file located in his/her home directory by appending a
VAR1
variable definition. When user 'prompt' logged out and loggedin again the $var1
variable is initialized and available for thenew terminal session.On the same principles we can define our bash prompt. The best place to do itis that bash initialization file
.~/bashrc
. Open up your ~/.bashrc
file and add/edit the line defining a PS1
variableto something like:NOTE: Your ~/.barshrc file may differ from the example below !
or similarly:
Temporary bash variable definition
A temporary bash variable lasts only as long as the current terminal session.This is tome by an export command.
As you can see the variable $VAR2
is not defined when usercloses his/her terminal session. The permanent variable $VAR1
isalways defined from the bash initialization file: ~/.bash_profile
.As we can use an export command to define new bash variables we can also use itto modify a bash prompt $PS1
variable. To change a current bashprompt to display only time we could do:Changing foreground and background bash prompt colors
Syntax for changing colors in the bash is as follows:
Bash color codes:
Jun 19, 2018 Each document that you have on your Mac is associated with a default application which macOS uses to open the. A File Type's Default App in macOS. MacBook Pro 15. Macos 15 default application for file type. May 23, 2016 Changing the Default Application for File Types in OS X. It’s really easy to change the default application a type of file opens in. Just click on one of the files and choose File Get Info from the main menu or use the Cmd+I keyboard shortcut. You can also right-click, Ctrl-click, or two-finger clicking the file and select “Get Info”.
Bash Prompt Examples
Macos Bash Prompt For Input With Default Download
To get you started with your new bash prompt here are couple examples:
Display current Time
Counting Files in the Current Directory
Macos Bash Prompt For Input With Default Windows 10
This bash prompt displays current number of files and directories in thecurrent directory.