Strange behaviour redirecting man pages
I wanted to redirect mc's man page to a text file using man mc > mc, but I accidentally executed man mc > mc grep. What resulted was a text file named mc containing two concatenated mc man pages.
I then tried man ls > 1 abc, which resulted in text file named 1 containing the ls man page and an error message in the terminal: No manual entry for abc.
Next I tried man du > du ls tac. I expected three concatenated du man pages, but what actually resulted was a text file named du containing the man pages of du, ls and tac concatenated.
Why did each command produced the results it did?
io-redirection man
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
add a comment |
I wanted to redirect mc's man page to a text file using man mc > mc, but I accidentally executed man mc > mc grep. What resulted was a text file named mc containing two concatenated mc man pages.
I then tried man ls > 1 abc, which resulted in text file named 1 containing the ls man page and an error message in the terminal: No manual entry for abc.
Next I tried man du > du ls tac. I expected three concatenated du man pages, but what actually resulted was a text file named du containing the man pages of du, ls and tac concatenated.
Why did each command produced the results it did?
io-redirection man
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
In the first case, what was the resulting text file’s name? (Presumablymc...)
– Stephen Kitt
Dec 23 '18 at 16:07
@Stephen Kitt: Yes,mc.
– EmmaV
Dec 23 '18 at 16:11
I can't reproduce the first finding - I getmcandgrepinmc, which is to be expected.
– tink
Dec 23 '18 at 16:41
I would expectmcandgrepman pages in a file calledmcfor first example.
– ctrl-alt-delor
Dec 23 '18 at 16:45
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday
add a comment |
I wanted to redirect mc's man page to a text file using man mc > mc, but I accidentally executed man mc > mc grep. What resulted was a text file named mc containing two concatenated mc man pages.
I then tried man ls > 1 abc, which resulted in text file named 1 containing the ls man page and an error message in the terminal: No manual entry for abc.
Next I tried man du > du ls tac. I expected three concatenated du man pages, but what actually resulted was a text file named du containing the man pages of du, ls and tac concatenated.
Why did each command produced the results it did?
io-redirection man
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
I wanted to redirect mc's man page to a text file using man mc > mc, but I accidentally executed man mc > mc grep. What resulted was a text file named mc containing two concatenated mc man pages.
I then tried man ls > 1 abc, which resulted in text file named 1 containing the ls man page and an error message in the terminal: No manual entry for abc.
Next I tried man du > du ls tac. I expected three concatenated du man pages, but what actually resulted was a text file named du containing the man pages of du, ls and tac concatenated.
Why did each command produced the results it did?
io-redirection man
io-redirection man
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
edited Dec 23 '18 at 16:37
Jeff Schaller
39k1053125
39k1053125
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
asked Dec 23 '18 at 16:01
EmmaV
1,1091331
1,1091331
In the first case, what was the resulting text file’s name? (Presumablymc...)
– Stephen Kitt
Dec 23 '18 at 16:07
@Stephen Kitt: Yes,mc.
– EmmaV
Dec 23 '18 at 16:11
I can't reproduce the first finding - I getmcandgrepinmc, which is to be expected.
– tink
Dec 23 '18 at 16:41
I would expectmcandgrepman pages in a file calledmcfor first example.
– ctrl-alt-delor
Dec 23 '18 at 16:45
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday
add a comment |
In the first case, what was the resulting text file’s name? (Presumablymc...)
– Stephen Kitt
Dec 23 '18 at 16:07
@Stephen Kitt: Yes,mc.
– EmmaV
Dec 23 '18 at 16:11
I can't reproduce the first finding - I getmcandgrepinmc, which is to be expected.
– tink
Dec 23 '18 at 16:41
I would expectmcandgrepman pages in a file calledmcfor first example.
– ctrl-alt-delor
Dec 23 '18 at 16:45
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday
In the first case, what was the resulting text file’s name? (Presumably
mc...)– Stephen Kitt
Dec 23 '18 at 16:07
In the first case, what was the resulting text file’s name? (Presumably
mc...)– Stephen Kitt
Dec 23 '18 at 16:07
@Stephen Kitt: Yes,
mc.– EmmaV
Dec 23 '18 at 16:11
@Stephen Kitt: Yes,
mc.– EmmaV
Dec 23 '18 at 16:11
I can't reproduce the first finding - I get
mc and grep in mc, which is to be expected.– tink
Dec 23 '18 at 16:41
I can't reproduce the first finding - I get
mc and grep in mc, which is to be expected.– tink
Dec 23 '18 at 16:41
I would expect
mc and grep man pages in a file called mc for first example.– ctrl-alt-delor
Dec 23 '18 at 16:45
I would expect
mc and grep man pages in a file called mc for first example.– ctrl-alt-delor
Dec 23 '18 at 16:45
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday
add a comment |
2 Answers
2
active
oldest
votes
This is consistent with a relatively obscure part of the Bash manual, which states under the section Shell Grammar:
A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. The
first word specifies the command to be executed, and is passed as argument zero. The remaining words are passed as arguments to the invoked command.
(Emphasis mine.)
What that means is that you can "mix" any redirections in with the command and its arguments.
For example, echo > world hello is equivalent to echo hello > world.
In other words, when you run a command like man du > du ls tac, it is equivalent to running:
man du ls tac > du
That these three manpages all end up concatenated into a file named du is then the result of how man behaves when its output is being redirected or piped: it will no longer try to use a pager and will essentially act like cat.
answered Dec 23 '18 at 16:38
cryptarch
5116
add a comment |
Only for reference/curiosity:
I know I'm not answering your question but in case you need to redirect the content of a man page you can do it with col(1)
man 1 col | col -b -x > manfile.foo
answered Dec 24 '18 at 12:20
tntx
392
add a comment |
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2 Answers
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2 Answers
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active
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This is consistent with a relatively obscure part of the Bash manual, which states under the section Shell Grammar:
A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. The
first word specifies the command to be executed, and is passed as argument zero. The remaining words are passed as arguments to the invoked command.
(Emphasis mine.)
What that means is that you can "mix" any redirections in with the command and its arguments.
For example, echo > world hello is equivalent to echo hello > world.
In other words, when you run a command like man du > du ls tac, it is equivalent to running:
man du ls tac > du
That these three manpages all end up concatenated into a file named du is then the result of how man behaves when its output is being redirected or piped: it will no longer try to use a pager and will essentially act like cat.
answered Dec 23 '18 at 16:38
cryptarch
5116
add a comment |
This is consistent with a relatively obscure part of the Bash manual, which states under the section Shell Grammar:
A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. The
first word specifies the command to be executed, and is passed as argument zero. The remaining words are passed as arguments to the invoked command.
(Emphasis mine.)
What that means is that you can "mix" any redirections in with the command and its arguments.
For example, echo > world hello is equivalent to echo hello > world.
In other words, when you run a command like man du > du ls tac, it is equivalent to running:
man du ls tac > du
That these three manpages all end up concatenated into a file named du is then the result of how man behaves when its output is being redirected or piped: it will no longer try to use a pager and will essentially act like cat.
answered Dec 23 '18 at 16:38
cryptarch
5116
add a comment |
This is consistent with a relatively obscure part of the Bash manual, which states under the section Shell Grammar:
A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. The
first word specifies the command to be executed, and is passed as argument zero. The remaining words are passed as arguments to the invoked command.
(Emphasis mine.)
What that means is that you can "mix" any redirections in with the command and its arguments.
For example, echo > world hello is equivalent to echo hello > world.
In other words, when you run a command like man du > du ls tac, it is equivalent to running:
man du ls tac > du
That these three manpages all end up concatenated into a file named du is then the result of how man behaves when its output is being redirected or piped: it will no longer try to use a pager and will essentially act like cat.
answered Dec 23 '18 at 16:38
cryptarch
5116
This is consistent with a relatively obscure part of the Bash manual, which states under the section Shell Grammar:
A simple command is a sequence of optional variable assignments followed by blank-separated words and redirections, and terminated by a control operator. The
first word specifies the command to be executed, and is passed as argument zero. The remaining words are passed as arguments to the invoked command.
(Emphasis mine.)
What that means is that you can "mix" any redirections in with the command and its arguments.
For example, echo > world hello is equivalent to echo hello > world.
In other words, when you run a command like man du > du ls tac, it is equivalent to running:
man du ls tac > du
That these three manpages all end up concatenated into a file named du is then the result of how man behaves when its output is being redirected or piped: it will no longer try to use a pager and will essentially act like cat.
answered Dec 23 '18 at 16:38
cryptarch
5116
answered Dec 23 '18 at 16:38
cryptarch
5116
answered Dec 23 '18 at 16:38
cryptarch
5116
answered Dec 23 '18 at 16:38
cryptarch
5116
5116
add a comment |
add a comment |
Only for reference/curiosity:
I know I'm not answering your question but in case you need to redirect the content of a man page you can do it with col(1)
man 1 col | col -b -x > manfile.foo
answered Dec 24 '18 at 12:20
tntx
392
add a comment |
Only for reference/curiosity:
I know I'm not answering your question but in case you need to redirect the content of a man page you can do it with col(1)
man 1 col | col -b -x > manfile.foo
answered Dec 24 '18 at 12:20
tntx
392
add a comment |
Only for reference/curiosity:
I know I'm not answering your question but in case you need to redirect the content of a man page you can do it with col(1)
man 1 col | col -b -x > manfile.foo
answered Dec 24 '18 at 12:20
tntx
392
Only for reference/curiosity:
I know I'm not answering your question but in case you need to redirect the content of a man page you can do it with col(1)
man 1 col | col -b -x > manfile.foo
answered Dec 24 '18 at 12:20
tntx
392
answered Dec 24 '18 at 12:20
tntx
392
answered Dec 24 '18 at 12:20
tntx
392
answered Dec 24 '18 at 12:20
tntx
392
392
add a comment |
add a comment |
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In the first case, what was the resulting text file’s name? (Presumably
mc...)– Stephen Kitt
Dec 23 '18 at 16:07
@Stephen Kitt: Yes,
mc.– EmmaV
Dec 23 '18 at 16:11
I can't reproduce the first finding - I get
mcandgrepinmc, which is to be expected.– tink
Dec 23 '18 at 16:41
I would expect
mcandgrepman pages in a file calledmcfor first example.– ctrl-alt-delor
Dec 23 '18 at 16:45
Hi EmmaV, I wondered if you would consider accepting my Answer? If you think it could use improvement in some way, please let me know how.
– cryptarch
yesterday