Bash&Printf:我怎样才能正确填充和截断？

Question

在Bash ......

我知道如何用printf正确填充

printf "%-10s" "potato"

我知道如何用printf截断

printf "%.10s" "potatos are my best friends"

我怎么能同时做到这两件事？

LIST="aaa bbbbb ccc ddddd"
for ITEM in $LIST; do
  printf "%-.4s blah" $ITEM
done

这打印

aaa blah
bbbbb blah
ccc blah
ddddd blah

我想要它打印

aaa  blah
bbbb blah
ccc  blah
dddd blah

我宁愿不做这样的事情(除非别无选择):

LIST="aaa bbbbb ccc ddddd"
for ITEM in $LIST; do
  printf "%-4s blah" $(printf "%.4s" "$ITEM")
done

虽然,显然,这是有效的(感觉丑陋和hackish).

Answer 1

您可以使用它printf "%-4.4s来获取输出中的两种格式:

for ITEM in $LIST; do printf "%-4.4s blah\n" "$ITEM"; done
aaa  blah
bbbb blah
ccc  blah
dddd blah