if [ $bluetooth != "off" ] && [ $(treehouses detect bluetooth) ]; thenif [ ! $(treehouses detect wifi) ]; then connectiontype="ethernet"; fi; # default network when no wifils -l $(getfilename)# getfilename outputs 1 filels -l "$(getfilename)" # getfilename outputs multiple files, linefeed separatedgetfilename | while IFS='' read -r linedo ls -l "$line"doneWhen command expansions are unquoted, word splitting and globbing will occur. This often manifests itself by breaking when filenames contain spaces.
Trying to fix it by adding quotes or escapes to the data will not work. Instead, quote the command substitution itself.
If the command substitution outputs multiple pieces of data, use a loop instead.
In rare cases you actually want word splitting, such as in
gcc $(pkg-config --libs openssl) client.cThis is because pkg-config outputs -lssl -lcrypto, which you want to break up by spaces into -lssl and -lcrypto. An alternative is to put the variables to an array and expand it:
args=( $(pkg-config --libs openssl) )gcc "${args[@]}" client.cThe power of using an array becomes evident when you want to combine, for example, the command result with user-provided arguments:
compile () { args=( $(pkg-config --libs openssl) "${@}" ) gcc "${args[@]}" client.c}compile -DDEBUG+ gcc -lssl -lcrypto -DDEBUG client.cOriginal content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.
ls -l $(getfilename)# getfilename outputs 1 filels -l "$(getfilename)" # getfilename outputs multiple files, linefeed separatedgetfilename | while IFS='' read -r linedo ls -l "$line"doneWhen command expansions are unquoted, word splitting and globbing will occur. This often manifests itself by breaking when filenames contain spaces.
Trying to fix it by adding quotes or escapes to the data will not work. Instead, quote the command substitution itself.
If the command substitution outputs multiple pieces of data, use a loop instead.
In rare cases you actually want word splitting, such as in
gcc $(pkg-config --libs openssl) client.cThis is because pkg-config outputs -lssl -lcrypto, which you want to break up by spaces into -lssl and -lcrypto. An alternative is to put the variables to an array and expand it:
args=( $(pkg-config --libs openssl) )gcc "${args[@]}" client.cThe power of using an array becomes evident when you want to combine, for example, the command result with user-provided arguments:
compile () { args=( $(pkg-config --libs openssl) "${@}" ) gcc "${args[@]}" client.c}compile -DDEBUG+ gcc -lssl -lcrypto -DDEBUG client.cOriginal content from the ShellCheck https://github.com/koalaman/shellcheck/wiki.