Question

我的printf语句在终端窗口中无法正确显示。前两个显示正确但第三个printf "Writing to %s$output%s" "$biwhite" "$color_off"未显示，除了$output的最后几个字符

感觉就像某种错误。如果我将echo替换为printf，则行正确显示，减去颜色。我已经尝试将所有语句放在一个printf中，结果相同。好像printf真的讨厌那句话。我对可能导致它的原因感到茫然。我在OSX工作。

biwhite=$(tput bold)$(tput setaf 7)
#bired=$(tput bold)$(tput setaf 1)
color_off=$(tput sgr0)
date="$(date +%Y%m%d)"


while [[ $# -gt 0 ]] ; do

input="$1" #name $input as the first arugment sent to script

if [ -d "$input" ] ; then   #if argment is a directory, run md5deep
  target="${input%/}" #strip the trailing /, if any
  target="${target##*/}" #drop the leading directory componenets i.e. get basename
  output="$input"/"$target"_"$date"_checksums.md5 #set .md5 file to $output
  printf "%s${input##*/}%s is a directory.\n" "$biwhite" "$color_off"
  printf "Making checksums of all files in %s$input%s\n" "$biwhite" "$color_off"
  printf "Writing to %s$output%s" "$biwhite" "$color_off"
  md5deep -bre "$input" >> "$output" #create md5 hash (hashes) of $input and write results to $output
fi
shift

done

Answer 1

一般来说，printf的格式字符串参数应该是常量。因此：

printf '%s%s%s is a directory.\n' "$biwhite" "${input##*/}" "$color_off" # GOOD
printf 'Writing to %s%s%s\n' "$biwhite" "$output" "$color_off"           # GOOD

...或...

printf '%s is a directory.\n' "$biwhite${input##*/}$color_off"           # GOOD
printf 'Writing to %s\n' "$biwhite$output$color_off"                     # GOOD

相反：

printf "%s${input##*/}%s is a directory.\n" "$biwhite" "$color_off"      # BAD
printf "Writing to %s$output%s\n" "$biwhite" "$color_off"                # BAD

否则，行为很难预测：

%内的任何"$output"符号都会摒弃其他位置参数的解释。
任何反斜杠转义序列都将替换为引用的字符 - \t的文字标签，\r的回车符等。（如果您想要这样，在您希望进行此类替换的特定位置使用%b而不是%s。

printf无法在bash

1 个答案: