Double quote to prevent globbing and word splitting
35valgrind_cmd+=" $executable_path"
36
37# Run the Valgrind command
38timeout --signal=SIGINT 60s $valgrind_cmd39
40exit_code=$?
41Double quote to prevent globbing and word splitting
17script_dir="$( cd "$( dirname "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
18
19# Attempt to copy the suppressions files from OpenCV install to project directory.
20cp /usr/local/share/opencv*/*.supp $script_dir21
22# Find all .supp files in the same directory as the script
23supp_files=$(find "$script_dir" -maxdepth 1 -type f -name "*.supp")Double quote to prevent globbing and word splitting
41 echo "Make sure to disconnect from the network before trying to reach the internet!"
42fi
43
44if [ $1 = "on" ] || [ $1 = "off" ]; then45 echo "Restarting network-manager"
46 service network-manager restart
47 echo "Restarting networking"Double quote to prevent globbing and word splitting
41 echo "Make sure to disconnect from the network before trying to reach the internet!"
42fi
43
44if [ $1 = "on" ] || [ $1 = "off" ]; then45 echo "Restarting network-manager"
46 service network-manager restart
47 echo "Restarting networking"Double quote to prevent globbing and word splitting
20 echo "" >> "${NETWORK}"
21
22 echo "Static IP has been turned ON"
23elif [ $1 = "off" ]; then24 echo "Turning Off - Static IP"
25
26 echo "# interfaces(5) file used by ifup(8) and ifdown(8)" > "${NETWORK}"Double quote to prevent globbing and word splitting
2
3NETWORK=/etc/network/interfaces
4
5if [ $1 = "on" ]; then 6 echo "Turning On - Static IP"
7
8 echo "# interfaces(5) file used by ifup(8) and ifdown(8)" > "${NETWORK}"Double quote to prevent globbing and word splitting
18 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
19else
20 echo "Package version ${TENSORFLOW_VERSION} does not exist in the repository. Building the package."
21 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT 22
23 # Install BAZEL build system.
24 wget https://github.com/bazelbuild/bazelisk/releases/download/v1.19.0/bazelisk-linux-arm64Double quote to prevent globbing and word splitting
15# Check if the file exists
16if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
17 echo "Package version ${TENSORFLOW_VERSION} already exists in the repository. Skipping build."
18 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT 19else
20 echo "Package version ${TENSORFLOW_VERSION} does not exist in the repository. Building the package."
21 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
18 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
19else
20 echo "Package version ${TENSORFLOW_VERSION} does not exist in the repository. Building the package."
21 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT 22
23 # Install BAZEL build system.
24 curl -fsSL https://bazel.build/bazel-release.pub.gpg | gpg --dearmor >bazel-archive-keyring.gpgDouble quote to prevent globbing and word splitting
15# Check if the file exists
16if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
17 echo "Package version ${TENSORFLOW_VERSION} already exists in the repository. Skipping build."
18 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT 19else
20 echo "Package version ${TENSORFLOW_VERSION} does not exist in the repository. Building the package."
21 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${QUILL_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
12# Check if the file exists
13if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
14 echo "Package version ${QUILL_VERSION} already exists in the repository. Skipping build."
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT16else
17 echo "Package version ${QUILL_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${QUILL_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
12# Check if the file exists
13if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
14 echo "Package version ${QUILL_VERSION} already exists in the repository. Skipping build."
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT16else
17 echo "Package version ${QUILL_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
16 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
17else
18 echo "Package version ${TORCH_VERSION} does not exist in the repository. Building the package."
19 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT20
21 # Install dependencies.
22 apt update && apt install -y python3-numpy python-is-python3Double quote to prevent globbing and word splitting
13# Check if the file exists
14if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
15 echo "Package version ${TORCH_VERSION} already exists in the repository. Skipping build."
16 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT17else
18 echo "Package version ${TORCH_VERSION} does not exist in the repository. Building the package."
19 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
16 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
17else
18 echo "Package version ${TORCH_VERSION} does not exist in the repository. Building the package."
19 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT20
21 # Delete Old Packages
22 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
13# Check if the file exists
14if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
15 echo "Package version ${TORCH_VERSION} already exists in the repository. Skipping build."
16 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT17else
18 echo "Package version ${TORCH_VERSION} does not exist in the repository. Building the package."
19 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${OPENCV_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
12# Check if the file exists
13if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
14 echo "Package version ${OPENCV_VERSION} already exists in the repository. Skipping build."
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT16else
17 echo "Package version ${OPENCV_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${OPENCV_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
12# Check if the file exists
13if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
14 echo "Package version ${OPENCV_VERSION} already exists in the repository. Skipping build."
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT16else
17 echo "Package version ${OPENCV_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${GTEST_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkgDouble quote to prevent globbing and word splitting
12# Check if the file exists
13if curl --output /dev/null --silent --head --fail "$FILE_URL"; then
14 echo "Package version ${GTEST_VERSION} already exists in the repository. Skipping build."
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT16else
17 echo "Package version ${GTEST_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUTDouble quote to prevent globbing and word splitting
15 echo "rebuilding_pkg=false" >> $GITHUB_OUTPUT
16else
17 echo "Package version ${GTEST_VERSION} does not exist in the repository. Building the package."
18 echo "rebuilding_pkg=true" >> $GITHUB_OUTPUT19
20 # Delete Old Packages
21 rm -rf /tmp/pkg
Description
Problematic code:
echo $1
for i in $*; do :; done # this one and the next one also apply to expanding arrays.
for i in $@; do :; done
Correct code:
echo "$1"
for i in "$@"; do :; done # or, 'for i; do'
Rationale
The first line in the problematic example looks like "print the first argument". In reality, it does a number of things:
- Split the first argument by IFS (spaces, tabs and line feeds).
- Expand each of the resulting strings as if it were a glob.
- Join all the resulting strings with spaces.
- Print the result.
The second line looks like "iterate through all arguments". This line is actually shorthand for the following steps:
- Join all the arguments by the first character of IFS (space)
- Split them by IFS
- Expand each of them as globs
- Iterate on the resulting list.
The third line skips the joining part.
Quoting variables prevents word splitting and glob expansion, and prevents the script from breaking when input contains spaces, line feeds, glob characters and such.
Strictly speaking, only expansions themselves need to be quoted, but for stylistic reasons, entire arguments with multiple variable and literal parts are often quoted as one:
$HOME/$dir/dist/bin/$file # Unquoted (bad)
"$HOME"/"$dir"/dist/bin/"$file" # Minimal quoting (good)
"$HOME/$dir/dist/bin/$file" # Canonical quoting (good)
When quoting composite arguments, make sure to exclude globs and brace expansions, which lose their special meaning in double quotes: "$HOME/$dir/src/*.c" will not expand, but "$HOME/$dir/src"/*.c will.
Note that $( ) starts a new context, and variables in it have to be quoted independently:
echo "This $variable is quoted $(but this $variable is not)"
echo "This $variable is quoted $(and now this "$variable" is too)"
Exceptions
Sometimes you want to split on spaces, like when building a command line:
options="-j 5 -B"
make $options file
Just quoting this doesn't work. Instead, you should have used an array (bash, ksh, zsh):
options=(-j 5 -B) # ksh: set -A options -- -j 5 -B
make "${options[@]}" file
or a function (POSIX):
make_with_flags() { make -j 5 -B "$@"; }
make_with_flags file
To split on spaces but not perform glob expansion, POSIX has a set -f to disable globbing. You can disable word splitting by setting IFS=''.
Similarly, you might want an optional argument:
debug=""
[[ $1 == "--trace-commands" ]] && debug="-x"
bash $debug script
Quoting this doesn't work, since in the default case, "$debug" would expand to one empty argument while $debug would expand into zero arguments. In this case, you can use an array with zero or one elements as outlined above, or you can use an unquoted expansion with an alternate value:
debug=""
[[ $1 == "--trace-commands" ]] && debug="yes"
bash ${debug:+"-x"} script
This is better than an unquoted value because the alternative value can be properly quoted, e.g. wget ${output:+ -o "$output"}.
Here are two common cases where this warning seems unnecessary but may still be beneficial:
cmd <<< $var # Requires quoting on Bash 3 (but not 4+)
: ${var=default} # Should be quoted to avoid DoS when var='*/*/*/*/*/*'