Read a variable in bash with a default value

Question

I need to read a value from the terminal in a bash script   I would like to be able to provide a default value that the user can change     Please enter your name  Ricardo    In this script the prompt is  Please enter your name    the default value is  Ricardo  and the cursor would be after the default value   Is there a way to do this in a bash script

User · Answer

Script for calculating various values in MB echo  Please enter some input    read input variable echo  input variable   awk    foo    1   1024   1024   print foo  MB

User · Answer

In Bash 4   name  Ricardo  read -e -i   name  -p  Please enter your name    input name    input - name     This displays the name after the prompt like this   Please enter your name  Ricardo   with the cursor at the end of the name and allows the user to edit it  The last line is optional and forces the name to be the original default if the user erases the input or default  submitting a null

User · Answer

name Ricardo echo  Please enter your name   name  c  read newname   -n   newname     amp  amp  name  newname   Set the default  print it  read a new value  if there is a new value  use it in place of the default   There is  or was  some variations between shells and systems on how to suppress a newline at the end of a prompt   The   c  notation seems to work on MacOS X 10 6 3 with a 3 x bash  and works on most variants of Unix derived from System V  using Bourne or Korn shells   Also note that the user would probably not realize what is going on behind the scenes  their new data would be entered after the name already on the screen   It might be better to format it   echo  Please enter your name   name    c

User · Answer

You can use parameter expansion  e g  read -p  quot Enter your name  Richard    quot  name name   name -Richard  echo  name  Including the default value in the prompt between brackets is a fairly common convention What does the  -Richard part do  From the bash manual     parameter -word  If parameter is unset or null  the expansion of word is substituted  Otherwise  the value of parameter is substituted   Also worth noting that     In each of the cases below  word is subject to tilde expansion  parameter expansion  command substitution  and arithmetic expansion   So if you use webpath   webpath -  httpdocs  you will get a result of  home user expanded path httpdocs not   httpdocs  etc

User · Answer

read -e -p  Enter Your Name   -i  Ricardo  NAME  echo  NAME

User · Answer

The -e and -t parameter does not work together  i tried some expressions and the result was the following code snippet    QMESSAGE  SHOULD I DO YES OR NO  YMESSAGE  I DO  NMESSAGE  I DO NOT  FMESSAGE  PLEASE ENTER Y or N  COUNTDOWN 2 DEFAULTVALUE n  ----------------------------------------------------------------  function REQUEST      read -n1 -t COUNTDOWN -p   QMESSAGE   Y N   INPUT     INPUT   INPUT - DEFAULTVALUE      if      INPUT     y  -o   INPUT     Y     then         echo -e   n YMESSAGE n           COMMANDEXECUTION     elif        INPUT     n  -o   INPUT     N     then         echo -e   n NMESSAGE n           COMMANDEXECUTION     else         echo -e   n FMESSAGE n      REQUEST     fi   REQUEST

User · Answer

I found this question  looking for a way to present something like   Something interesting happened   Proceed  Y n q     Using the above examples I deduced this -  echo -n  Something interesting happened     DEFAULT  y  read -e -p  Proceed  Y n q    PROCEED   adopt the default  if  enter  given PROCEED    PROCEED -  DEFAULT      change to lower case to simplify following if PROCEED    PROCEED       condition for specific letter if      PROCEED       q      then   echo  Quitting    exit   condition for non specific letter  ie anything other than q y    if you want to have the active  y  code in the last section elif      PROCEED       y      then   echo  Not Proceeding  else   echo  Proceeding      do proceeding code in here fi   Hope that helps someone to not have to think out the logic  if they encounter the same problem

User · Answer

Code   IN PATH DEFAULT   tmp input txt  read -p  Please enter IN PATH   IN PATH DEFAULT     IN PATH IN PATH    IN PATH - IN PATH DEFAULT    OUT PATH DEFAULT   tmp output txt  read -p  Please enter OUT PATH   OUT PATH DEFAULT     OUT PATH OUT PATH    OUT PATH - OUT PATH DEFAULT    echo  Input   IN PATH Output   OUT PATH    Sample run   Please enter IN PATH   tmp input txt    Please enter OUT PATH   tmp output txt     out txt Input   tmp input txt Output    out txt

User · Answer

I ve just used this pattern  which I prefer   read name    name   nobody

[bash] Read a variable in bash with a default value

Examples related to bash

Examples related to shell