8

I'm messing around with scripting, I am able to create a script which when run prompts me for a name for a new dir, creates it then creates several files, echoes lines out, then deletes it all.

What I would like to do is morph it slightly so it creates and names the directory all by itself!

Seems a pointless exercise I know, but messing around with it is the best way I learn.

Here is my current script:

#!/bin/bash   
echo "Give a directory name to create:"    
read NEW_DIR    
ORIG_DIR=$(pwd)    
[[ -d $NEW_DIR ]] && echo $NEW_DIR already exists, aborting && exit    
mkdir  $NEW_DIR    
cd $NEW_DIR    
pwd    
for n in 9 8 7 6 5 4 3 2 1 0    
do        
touch file$n    
done

ls file?    

for names in file?    
do       
echo This file is named $names > $names    
done

cat file?

cd $ORIG_DIR

rm -rf $NEW_DIR

echo "Goodbye"
Zanna
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SimplySimplified
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  • what do you mean by *it creates and names the directory all by itself*? how will the script choose the names? – Yaron Sep 04 '17 at 09:38
  • As in instead of me typing a directory name when prompted it's already written in the script. – SimplySimplified Sep 04 '17 at 09:41
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    do you mean by setting hard-coded value for a directory name in the script (which will replace the *read* operation)? – Yaron Sep 04 '17 at 09:43
  • Yes, just that! – SimplySimplified Sep 04 '17 at 09:47
  • You might want to dive into [Bash Parameter Expansion](http://wiki.bash-hackers.org/syntax/pe) and [Brace Expansion](http://wiki.bash-hackers.org/syntax/expansion/brace), e. g. `9 8 7 6 5 4 3 2 1 0` in your code can be shortened to `{9..0}` and you might as well replace the whole `for` loop with `touch file{9..0}`. – dessert Sep 04 '17 at 11:00
  • if you want to learn something:-) you might want to use `pushd` and `popd` instead of assigning `pwd` to variables. also, in your line `echo This file is named` you should use `>>`, not `>`, if you want to get more than the last line. And maybe `mkdir -p` could help you to avoid the `-d` test. (possibly the `-p` flag is not available everywhere) – ohno Sep 04 '17 at 13:16
  • Please get into the habit of quoting your variables. Always. For example, `cd "${NEW_DIR}"`, `[[ -d "${NEW_DIR}" ]]` and `> "${names}"`. This prevents potentially serious errors when variables contain spaces and certain other characters. (The curly brackets are optional except in rare cases.) – Paddy Landau Sep 06 '17 at 08:38
  • As long as you're playing to learn, `echo -n` prints your prompt without the trailing newline, so you get the cursor after the prompt. I think it looks nicer. – MDeBusk Jun 02 '22 at 23:19

4 Answers4

6

Instead of using the read command in order to get the value ofNEW_DIR from the input, You can set hard-coded value for the NEW_DIR variable in the following way:

replace the following line in your script:

read NEW_DIR

with the following line:

NEW_DIR="new_dir_hard_coded_value"

Link for more info about bash-scripting-tutorial/bash-variables

Yaron
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6

If you want a surprise, instead of hardcoding the name you could use a technique to generate a random string, for example

NEW_DIR=$(tr -cd '[:alnum:]' < /dev/urandom | fold -w8 | head -n1)

This sets NEW_DIR to a string of eight alphanumeric characters. Every time you run the script, the new directory will have a different random name...

Or to get a random word, pick a dictionary from /usr/share/dict/ and use shuf, for example:

$ shuf -n1 /usr/share/dict/british-english
soupier
$ shuf -n1 /usr/share/dict/british-english
penguins

So

NEW_DIR=$(shuf -n1 /usr/share/dict/british-english)
mkdir "$NEW_DIR"
...
Zanna
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3

Instead of prompting for user input, you can hardcode values into scripts by using variable assignment operator (=). Thus, the following two lines,

echo "Give a directory name to create:"
read NEW_DIR

can be replaced by a single line.

NEW_DIR="whatever_name_you_please"


BTW, I know this is not relevant to the question but in the for loop you used in your script, you can write shorthand code for the range. Instead of 9 8 7 6 5 4 3 2 1 0, you may write it as

 for n in {9..0}
Mukesh Sai Kumar
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3

You could even go one step further: You could tell "read" to offer a proposition for the folder name, accept it by pressing return or change it as you like:

read -p "Give a directory name to create: " -ei "default_name" NEW_DIR;

this would show a line:

Give a directory name to create: default_name

To combine with the above suggestions, you could do the following:

# pre-set NEW_DIR to a value or to any random string 
# as suggested in the other answers
NEW_DIR="default_name"

# Prompt for new directory name, suggesting previously selected default answer
read -p "Give a directory name to create: " -ei "$NEW_DIR" NEW_DIR;

Note that read -p "text" will prompt for the text and ask for the answer in the same line. If you want to stick to your code and have it ask for the 2-line-format you could do

echo "Give a directory name to create:"  
read -ei "$NEW_DIR" NEW_DIR
stealz
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