bash - Passing a string value will fail to find the file -


i write shell try collect file file path current directory if exists:

collect_file() {   fpath=$1   echo $fpath   if [ -e $fpath ];      fname=`basename $fpath`     `cp $1 $fname`     retval=$?     if [ $retval == 0 ];       echo "collect file '$fpath'"     else       echo "error: fail copy file '$fpath'"     fi    else     echo "error: file '$fpath' not found"   fi   }

now, if pass bare value ~/.gitconfig, succeed, when pass string value "~/.gitconfig", fail.

collect_file ~/.gitconfig        # succeed copy file collect_file "~/.gitconfig"      # fail

shows:

# results bare value /users/xaree/.gitconfig collect file '/users/xaree/.gitconfig'  # results string value ~/.gitconfig error: file '~/.gitconfig' not found

why , how can fix it?

the following refers file in user's home directory:

~/.gitconfig

by contrast, following refers file in directory named ~:

"~/.gitconfig"

~/ interpreted home directory when shell performs tilde expansion. shell perform tilde expansion when ! unquoted. if string quoted, ~ means ~ , nothing else.

examples

observe tilde expansion performed 1 of following 3 statements:

$ echo "~/.bashrc" ~/.bashrc $ echo ~"/.bashrc" ~/.bashrc $ echo ~/".bashrc" /home/john1024/.bashrc

forcing tilde expansion

tilde expansion, implemented shell, offers many features many special cases. force general tilde expansion using eval introduce many security issues. basic case, however, can safely replace ~/ in variable $home/ follows:

fpath="${fpath/~\//$home\/}"

a problem above replace first occurrence of ~/ if string not start ~/. avoid that, can use:

[ "${fpath#\~/}" != "$fpath" ] && fpath="${fpath/~\//$home\/}"

this tests sure string starts ~/ before makes substitution.


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