1 shellcheck 简介
今天发现的一款神器，如果你日常会接触到shell脚本，或者说自己需要写一些shell脚本，那么强烈建议你用下这个工具。
shellcheck一个静态的shell脚本分析工具，可以判断脚本哪里有异常，哪里可以优化，并且会给出对应的解决办法。几年前我咋没发现这个，后悔。。。
一个简单的示例：
这款工具不仅适用于初学者，对于中高级使用者帮助更大。
2 安装
github可以访问的直接到如下链接去下载就可以，目前支持多个终端，也有web可访问
https://github.com/koalaman/shellcheck
github如果无法访问的话，可以后台直接私信
web访问地址：
https://www.shellcheck.net/
使用方式：
3 shell脚本中的一些常见错误
- 常见错误引用
echo $1 # Unquoted variables find . -name *.ogg # Unquoted find/grep patterns rm "~/my file.txt" # Quoted tilde expansion v='--verbose="true"'; cmd $v # Literal quotes in variables for f in "*.ogg" # Incorrectly quoted 'for' loops touch $@ # Unquoted $@ echo 'Don't forget to restart!' # Singlequote closed by apostrophe echo 'Don\'t try this at home' # Attempting to escape ' in '' echo 'Path is $PATH' # Variables in single quotes trap "echo Took ${SECONDS}s" 0 # Prematurely expanded trap unset var[i] # Array index treated as glob 常见错误条件语句
[[ n != 0 ]] # Constant test expressions [[ -e *.mpg ]] # Existence checks of globs [[ $foo==0 ]] # Always true due to missing spaces [[ -n "$foo " ]] # Always true due to literals [[ $foo =~ "fo+" ]] # Quoted regex in =~ [ foo =~ re ] # Unsupported [ ] operators [ $1 -eq "shellcheck" ] # Numerical comparison of strings [ $n && $m ] # && in [ .. ] [ grep -q foo file ] # Command without $(..) [[ "$$file" == *.jpg ]] # Comparisons that can't succeed (( 1 -lt 2 )) # Using test operators in ((..)) [ x ] & [ y ] | [ z ] # Accidental backgrounding and piping误用的命令
grep '*foo*' file # Globs in regex contexts find . -exec foo {} && bar {} \; # Prematurely terminated find -exec sudo echo 'Var=42' > /etc/profile # Redirecting sudo time --format=%s sleep 10 # Passing time(1) flags to time builtin while read h; do ssh "$h" uptime # Commands eating while loop input alias archive='mv $1 /backup' # Defining aliases with arguments tr -cd '[a-zA-Z0-9]' # [] around ranges in tr exec foo; echo "Done!" # Misused 'exec' find -name \*.bak -o -name \*~ -delete # Implicit precedence in find # find . -exec foo > bar \; # Redirections in find f() { whoami; }; sudo f # External use of internal functions- 初学者常见错误
var = 42 # Spaces around = in assignments $foo=42 # $ in assignments for $var in *; do ... # $ in for loop variables var$n="Hello" # Wrong indirect assignment echo ${var$n} # Wrong indirect reference var=(1, 2, 3) # Comma separated arrays array=( [index] = value ) # Incorrect index initialization echo $var[14] # Missing {} in array references echo "Argument 10 is $10" # Positional parameter misreference if $(myfunction); then ..; fi # Wrapping commands in $() else if othercondition; then .. # Using 'else if' f; f() { echo "hello world; } # Using function before definition [ false ] # 'false' being true if ( -f file ) # Using (..) instead of test
