0

考虑一下：

cat > mytestfile.txt <<'EOF'
    "'iceberg'"
    "'ice cliff'"
    "'ice field'"
    "'inlet'"
    "'island'"
    "'islet'"
    "'isthmus'"
EOF

perl -dpi -e 's/ice/dice/' mytestfile.txt

当调试器运行时，我尝试向 print 添加一个操作$_，但是：

$ perl -dpi -e 's/ice/dice/' mytestfile.txt 

Loading DB routines from perl5db.pl version 1.39_10
Editor support available.

Enter h or 'h h' for help, or 'man perldebug' for more help.

main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
  DB<1> n
main::(-e:1):   s/ice/dice/
  DB<1> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
  DB<1> print $_

  DB<2> n
main::(-e:1):   s/ice/dice/
  DB<2> print $_

  DB<3> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
  DB<3> p $_
    "'ddiceberg'"

  DB<4> print "$_"

...
  DB<1> a 0 print "$_";
  DB<2> L  
  DB<3> L a
  DB<4> n
...
  DB<6> a 1 print "$_"
  DB<7> L a
-e:
 1: s/ice/dice/
    action:  print "$_"
  DB<8> n
main::(-e:1):   s/ice/dice/
  DB<8> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
  DB<8> n
main::(-e:1):   s/ice/dice/
  DB<8> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
  DB<8> n
...
  DB<8> a 1 p $_
  DB<9> L a
-e:
 1: s/ice/dice/
    action:  p $_
  DB<10> n
main::(-e:1):   s/ice/dice/
Can't locate object method "p" via package "    "'ice cliff'"
" (perhaps you forgot to load "    "'ice cliff'"
"?) at (eval 13)[/usr/share/perl/5.18/perl5db.pl:732] line 1, <> line 3.
  DB<10> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
Can't locate object method "p" via package "    "'dice cliff'"
" (perhaps you forgot to load "    "'dice cliff'"
"?) at (eval 14)[/usr/share/perl/5.18/perl5db.pl:732] line 1, <> line 3.

...有问题：

  • 如果我这样做print $_，我会得到一个空字符串 - 如果我这样做p $_，我会得到一个变量的实际打印输出
  • 我无法在第 0 行添加操作
  • print $_在第 1 行，动作执行 - 但如果用作动作，它看起来不像，因为如前所述，它返回空字符串；但p $_即使它以交互模式打印，它在用作操作时也会引发错误。

那么我怎样才能让像“美元下划线”这样的东西$_打印每个循环作为调试-pie脚本的动作呢？

4

1 回答 1

1

通过如何在 perl 调试器的 < 操作中运行 `x` 命令得到它？，它是{ p $_：

  DB<1> { p $_
  DB<2> n
main::(-e:1):   s/ice/dice/
auto(-1)  DB<2> p $_
    "'iceberg'"

  DB<3> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
auto(-1)  DB<3> p $_
    "'diceberg'"

  DB<4> n
main::(-e:1):   s/ice/dice/
auto(-1)  DB<4> p $_
    "'ice cliff'"

  DB<5> n
main::(-e:0):   BEGIN { require 'perl5db.pl' };LINE: while (<>) {
auto(-1)  DB<5> p $_
    "'dice cliff'"
于 2016-12-17T17:28:03.500 回答