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Merge pull request #1026 from PeterDaveHello/patch-1 

Enable syntax highlight in README.md code block
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koalaman 2017-10-15 19:09:32 -07:00 committed by GitHub
parent 1491402dcb 76ad5dbb9f
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@ -148,8 +148,10 @@ On Solus:
From Docker Hub: From Docker Hub:
docker pull koalaman/shellcheck:latest # Or :v0.4.6 for a release version ```sh
docker run -v "$PWD:/mnt" koalaman/shellcheck myscript docker pull koalaman/shellcheck:latest # Or :v0.4.6 for a release version
docker run -v "$PWD:/mnt" koalaman/shellcheck myscript
```
or use `koalaman/shellcheck-alpine` if you want a larger Alpine Linux based image to extend. or use `koalaman/shellcheck-alpine` if you want a larger Alpine Linux based image to extend.
@ -209,12 +211,16 @@ This will compile ShellCheck and install it to your `~/.cabal/bin` directory.
Add this directory to your `PATH` (for bash, add this to your `~/.bashrc`): Add this directory to your `PATH` (for bash, add this to your `~/.bashrc`):
export PATH="$HOME/.cabal/bin:$PATH" ```sh
export PATH="$HOME/.cabal/bin:$PATH"
```
Log out and in again, and verify that your PATH is set up correctly: Log out and in again, and verify that your PATH is set up correctly:
$ which shellcheck ```sh
~/.cabal/bin/shellcheck $ which shellcheck
~/.cabal/bin/shellcheck
```
On native Windows, the `PATH` should already be set up, but the system On native Windows, the `PATH` should already be set up, but the system
may use a legacy codepage. In `cmd.exe`, `powershell.exe` and Powershell ISE, may use a legacy codepage. In `cmd.exe`, `powershell.exe` and Powershell ISE,
@ -242,129 +248,147 @@ So what kind of things does ShellCheck look for? Here is an incomplete list of d
ShellCheck can recognize several types of incorrect quoting: ShellCheck can recognize several types of incorrect quoting:
echo $1 # Unquoted variables ```sh
find . -name *.ogg # Unquoted find/grep patterns echo $1 # Unquoted variables
rm "~/my file.txt" # Quoted tilde expansion find . -name *.ogg # Unquoted find/grep patterns
v='--verbose="true"'; cmd $v # Literal quotes in variables rm "~/my file.txt" # Quoted tilde expansion
for f in "*.ogg" # Incorrectly quoted 'for' loops v='--verbose="true"'; cmd $v # Literal quotes in variables
touch $@ # Unquoted $@ for f in "*.ogg" # Incorrectly quoted 'for' loops
echo 'Don't forget to restart!' # Singlequote closed by apostrophe touch $@ # Unquoted $@
echo 'Don\'t try this at home' # Attempting to escape ' in '' echo 'Don't forget to restart!' # Singlequote closed by apostrophe
echo 'Path is $PATH' # Variables in single quotes echo 'Don\'t try this at home' # Attempting to escape ' in ''
trap "echo Took ${SECONDS}s" 0 # Prematurely expanded trap echo 'Path is $PATH' # Variables in single quotes
trap "echo Took ${SECONDS}s" 0 # Prematurely expanded trap
```
### Conditionals ### Conditionals
ShellCheck can recognize many types of incorrect test statements. ShellCheck can recognize many types of incorrect test statements.
[[ n != 0 ]] # Constant test expressions ```sh
[[ -e *.mpg ]] # Existence checks of globs [[ n != 0 ]] # Constant test expressions
[[ $foo==0 ]] # Always true due to missing spaces [[ -e *.mpg ]] # Existence checks of globs
[[ -n "$foo " ]] # Always true due to literals [[ $foo==0 ]] # Always true due to missing spaces
[[ $foo =~ "fo+" ]] # Quoted regex in =~ [[ -n "$foo " ]] # Always true due to literals
[ foo =~ re ] # Unsupported [ ] operators [[ $foo =~ "fo+" ]] # Quoted regex in =~
[ $1 -eq "shellcheck" ] # Numerical comparison of strings [ foo =~ re ] # Unsupported [ ] operators
[ $n && $m ] # && in [ .. ] [ $1 -eq "shellcheck" ] # Numerical comparison of strings
[ grep -q foo file ] # Command without $(..) [ $n && $m ] # && in [ .. ]
[[ "$$file" == *.jpg ]] # Comparisons that can't succeed [ grep -q foo file ] # Command without $(..)
(( 1 -lt 2 )) # Using test operators in ((..)) [[ "$$file" == *.jpg ]] # Comparisons that can't succeed
(( 1 -lt 2 )) # Using test operators in ((..))
```
### Frequently misused commands ### Frequently misused commands
ShellCheck can recognize instances where commands are used incorrectly: ShellCheck can recognize instances where commands are used incorrectly:
grep '*foo*' file # Globs in regex contexts ```sh
find . -exec foo {} && bar {} \; # Prematurely terminated find -exec grep '*foo*' file # Globs in regex contexts
sudo echo 'Var=42' > /etc/profile # Redirecting sudo find . -exec foo {} && bar {} \; # Prematurely terminated find -exec
time --format=%s sleep 10 # Passing time(1) flags to time builtin sudo echo 'Var=42' > /etc/profile # Redirecting sudo
while read h; do ssh "$h" uptime # Commands eating while loop input time --format=%s sleep 10 # Passing time(1) flags to time builtin
alias archive='mv $1 /backup' # Defining aliases with arguments while read h; do ssh "$h" uptime # Commands eating while loop input
tr -cd '[a-zA-Z0-9]' # [] around ranges in tr alias archive='mv $1 /backup' # Defining aliases with arguments
exec foo; echo "Done!" # Misused 'exec' tr -cd '[a-zA-Z0-9]' # [] around ranges in tr
find -name \*.bak -o -name \*~ -delete # Implicit precedence in find exec foo; echo "Done!" # Misused 'exec'
f() { whoami; }; sudo f # External use of internal functions find -name \*.bak -o -name \*~ -delete # Implicit precedence in find
f() { whoami; }; sudo f # External use of internal functions
```
### Common beginner's mistakes ### Common beginner's mistakes
ShellCheck recognizes many common beginner's syntax errors: ShellCheck recognizes many common beginner's syntax errors:
var = 42 # Spaces around = in assignments ```sh
$foo=42 # $ in assignments var = 42 # Spaces around = in assignments
for $var in *; do ... # $ in for loop variables $foo=42 # $ in assignments
var$n="Hello" # Wrong indirect assignment for $var in *; do ... # $ in for loop variables
echo ${var$n} # Wrong indirect reference var$n="Hello" # Wrong indirect assignment
var=(1, 2, 3) # Comma separated arrays echo ${var$n} # Wrong indirect reference
array=( [index] = value ) # Incorrect index initialization var=(1, 2, 3) # Comma separated arrays
echo "Argument 10 is $10" # Positional parameter misreference array=( [index] = value ) # Incorrect index initialization
if $(myfunction); then ..; fi # Wrapping commands in $() echo "Argument 10 is $10" # Positional parameter misreference
else if othercondition; then .. # Using 'else if' if $(myfunction); then ..; fi # Wrapping commands in $()
else if othercondition; then .. # Using 'else if'
```
### Style ### Style
ShellCheck can make suggestions to improve style: ShellCheck can make suggestions to improve style:
[[ -z $(find /tmp | grep mpg) ]] # Use grep -q instead ```sh
a >> log; b >> log; c >> log # Use a redirection block instead [[ -z $(find /tmp | grep mpg) ]] # Use grep -q instead
echo "The time is `date`" # Use $() instead a >> log; b >> log; c >> log # Use a redirection block instead
cd dir; process *; cd ..; # Use subshells instead echo "The time is `date`" # Use $() instead
echo $[1+2] # Use standard $((..)) instead of old $[] cd dir; process *; cd ..; # Use subshells instead
echo $(($RANDOM % 6)) # Don't use $ on variables in $((..)) echo $[1+2] # Use standard $((..)) instead of old $[]
echo "$(date)" # Useless use of echo echo $(($RANDOM % 6)) # Don't use $ on variables in $((..))
cat file | grep foo # Useless use of cat echo "$(date)" # Useless use of echo
cat file | grep foo # Useless use of cat
```
### Data and typing errors ### Data and typing errors
ShellCheck can recognize issues related to data and typing: ShellCheck can recognize issues related to data and typing:
args="$@" # Assigning arrays to strings ```sh
files=(foo bar); echo "$files" # Referencing arrays as strings args="$@" # Assigning arrays to strings
declare -A arr=(foo bar) # Associative arrays without index files=(foo bar); echo "$files" # Referencing arrays as strings
printf "%s\n" "Arguments: $@." # Concatenating strings and arrays declare -A arr=(foo bar) # Associative arrays without index
[[ $# > 2 ]] # Comparing numbers as strings printf "%s\n" "Arguments: $@." # Concatenating strings and arrays
var=World; echo "Hello " var # Unused lowercase variables [[ $# > 2 ]] # Comparing numbers as strings
echo "Hello $name" # Unassigned lowercase variables var=World; echo "Hello " var # Unused lowercase variables
cmd | read bar; echo $bar # Assignments in subshells echo "Hello $name" # Unassigned lowercase variables
cmd | read bar; echo $bar # Assignments in subshells
```
### Robustness ### Robustness
ShellCheck can make suggestions for improving the robustness of a script: ShellCheck can make suggestions for improving the robustness of a script:
rm -rf "$STEAMROOT/"* # Catastrophic rm ```sh
touch ./-l; ls * # Globs that could become options rm -rf "$STEAMROOT/"* # Catastrophic rm
find . -exec sh -c 'a && b {}' \; # Find -exec shell injection touch ./-l; ls * # Globs that could become options
printf "Hello $name" # Variables in printf format find . -exec sh -c 'a && b {}' \; # Find -exec shell injection
for f in $(ls *.txt); do # Iterating over ls output printf "Hello $name" # Variables in printf format
export MYVAR=$(cmd) # Masked exit codes for f in $(ls *.txt); do # Iterating over ls output
export MYVAR=$(cmd) # Masked exit codes
```
### Portability ### Portability
ShellCheck will warn when using features not supported by the shebang. For example, if you set the shebang to `#!/bin/sh`, ShellCheck will warn about portability issues similar to `checkbashisms`: ShellCheck will warn when using features not supported by the shebang. For example, if you set the shebang to `#!/bin/sh`, ShellCheck will warn about portability issues similar to `checkbashisms`:
echo {1..$n} # Works in ksh, but not bash/dash/sh ```sh
echo {1..10} # Works in ksh and bash, but not dash/sh echo {1..$n} # Works in ksh, but not bash/dash/sh
echo -n 42 # Works in ksh, bash and dash, undefined in sh echo {1..10} # Works in ksh and bash, but not dash/sh
trap 'exit 42' sigint # Unportable signal spec echo -n 42 # Works in ksh, bash and dash, undefined in sh
cmd &> file # Unportable redirection operator trap 'exit 42' sigint # Unportable signal spec
read foo < /dev/tcp/host/22 # Unportable intercepted files cmd &> file # Unportable redirection operator
foo-bar() { ..; } # Undefined/unsupported function name read foo < /dev/tcp/host/22 # Unportable intercepted files
[ $UID = 0 ] # Variable undefined in dash/sh foo-bar() { ..; } # Undefined/unsupported function name
local var=value # local is undefined in sh [ $UID = 0 ] # Variable undefined in dash/sh
time sleep 1 | sleep 5 # Undefined uses of 'time' local var=value # local is undefined in sh
time sleep 1 | sleep 5 # Undefined uses of 'time'
```
### Miscellaneous ### Miscellaneous
ShellCheck recognizes a menagerie of other issues: ShellCheck recognizes a menagerie of other issues:
PS1='\e[0;32m\$\e[0m ' # PS1 colors not in \[..\] ```sh
PATH="$PATH:~/bin" # Literal tilde in $PATH PS1='\e[0;32m\$\e[0m ' # PS1 colors not in \[..\]
rm “file” # Unicode quotes PATH="$PATH:~/bin" # Literal tilde in $PATH
echo "Hello world" # Carriage return / DOS line endings rm “file” # Unicode quotes
echo hello \ # Trailing spaces after \ echo "Hello world" # Carriage return / DOS line endings
var=42 echo $var # Expansion of inlined environment echo hello \ # Trailing spaces after \
#!/bin/bash -x -e # Common shebang errors var=42 echo $var # Expansion of inlined environment
echo $((n/180*100)) # Unnecessary loss of precision #!/bin/bash -x -e # Common shebang errors
ls *[:digit:].txt # Bad character class globs echo $((n/180*100)) # Unnecessary loss of precision
sed 's/foo/bar/' file > file # Redirecting to input ls *[:digit:].txt # Bad character class globs
sed 's/foo/bar/' file > file # Redirecting to input
```
## Testimonials ## Testimonials