-f $file_name doesn't work when using ~/file_name but works when using /home/james/file_name

James Ayres

6/8/23, 4:29 PM

This has been driving me nuts. I have a pretty simple script

#!/bin/bash

read -p "Enter changeList.txt file name: " file_name

if  [ -f $file_name ]; then
    echo "Reading File..."
    cat $file_name | grep "Change " | cut -d ' ' -f 2
    echo "Process complete"
else
    echo >&2 "File Note Found."
    exit 1
fi 

echo "Exiting..."
exit 0

I pass it a file ~/changeList.txt, that fails. I pass it /home/james/changeList.txt, and it works. I try

file_name=~/changeList.txt
[ -f $file_name ] && echo "true" || echo "false"

from my terminal and it returns true.
I am using Ubuntu on wsl 2, and I am signed in as james.

0 + 0

command-line

bash

scripts

windows-subsystem-for-linux

steeldriver

6/8/23, 6:49 PM

Related: [Why isn't tilde expansion performed on the input to read?](https://askubuntu.com/questions/1093906/why-isnt-tilde-expansion-performed-on-the-input-to-read)

Score:1

Ubuntu

choroba

6/8/23, 4:36 PM

Tilde expansion happens before variable expansion. In an assignment, the right hand side value undergoes tilde expansion, so the variable is assigned the full path. See man bash for details.

0 + 0

James Ayres

6/8/23, 4:53 PM

Do you know if there is a way to do tilde expansion from a string coming in or should I just not pass in a tilde?

choroba

6/8/23, 5:28 PM

`man bash` mentions `set expand-tilde On` with `read -e`, but I haven't been able to make it work.

Gordon Davisson

6/8/23, 7:43 PM

@JamesAyres There are a bunch of options (of varying degrees of complexity and reliability) under the stackoverflow question ["How to manually expand a special variable (ex: ~ tilde) in bash"](https://stackoverflow.com/questions/3963716/how-to-manually-expand-a-special-variable-ex-tilde-in-bash).

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: -f $file_name doesn't work when using ~/file_name but works when using /home/james/file_name

TH: -f $file_name ไม่ทำงานเมื่อใช้ ~/file_name แต่ใช้งานได้เมื่อใช้ /home/james/file_name

RO: -f $file_name nu funcționează când folosești ~/file_name, dar funcționează când folosești /home/james/file_name

RU: -f $file_name не работает при использовании ~/file_name, но работает при использовании /home/james/file_name

VI: -f $file_name không hoạt động khi sử dụng ~/file_name nhưng hoạt động khi sử dụng /home/james/file_name

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