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retag, as no linux specific. rephrase title to better fit the topic.
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Anthon
Anthon
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I can understand the statements like.

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1
  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I don't understand the statement below.:

bzip2 --version 2>&1 < /dev/null | head -n1

bzip2 --version 2>&1 < /dev/null | head -n1

I can understand the statements like.

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I don't understand the statement below.

bzip2 --version 2>&1 < /dev/null | head -n1

I can understand the statements like.

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I don't understand the statement:

bzip2 --version 2>&1 < /dev/null | head -n1
retag, as no linux specific. rephrase title to better fit the topic.
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edit approved Mar 1, 2015 at 13:14
越鸟巢南枝
edit approved Mar 1, 2015 at 13:14
越鸟巢南枝
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Redirect the standard IO streams explain this shell command with redirection and pipe

I can easily understand the statements like.

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I really don't understand the statement below. Please help.

bzip2 --version 2>&1 < /dev/null | head -n1

Redirect the standard IO streams

I can easily understand the statements like

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I really don't understand the statement below. Please help.

bzip2 --version 2>&1 < /dev/null | head -n1

explain this shell command with redirection and pipe

I can understand the statements like.

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I don't understand the statement below.

bzip2 --version 2>&1 < /dev/null | head -n1

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Yu Siu Ping
Yu Siu Ping
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Redirect the standard IO streams

I can easily understand the statements like

  1. bzip2 --version >/tmp/list_right 2>/tmp/list_error
  2. bzip2 --version >/tmp/list 2>&1

But I really don't understand the statement below. Please help.

bzip2 --version 2>&1 < /dev/null | head -n1