bashvariable-assignmentdouble-quotestilde-expansion

Tilde not expanded when quoting on the right hand side of a Bash variable assignment

I have made a directory ~/test_myDir

I then run the following bash script:

x="myDir"

dirName="~/test_$x"

cd $dirName
echo "hey" > test.txt

I get the following error:

test.sh: line 5: cd: ~/test_myDir: No such file or directory

I then remove the quotes from the second assignment:

x="myDir"

dirName=~/test_$x

cd $dirName
echo "hey" > test.txt

The script runs without error.

What is going on here? I ran into this issue in a larger, more complicated script, and I narrowed it down to my use of quotes in a variable assignment that contained another variable.

Still, from the error message, it looks like the full path is being expanded correctly in the "cd" call.

Solution

  • Quotation marks prevent expansion of ~. Replace ~ with $HOME or use dirName=~/"test_$x".

    From the manual's explanation of tilde expansion:

    Each variable assignment is checked for unquoted tilde-prefixes immediately following a : or the first =. In these cases, tilde expansion is also performed.