StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
14464573
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
0
CommunityOwnedDate
CreationDate
2013-01-22T17:31:41.253
FavoriteCount
0
LastActivityDate
2013-01-22T17:31:41.253
LastEditDate
LastEditorUserId
0
OwnerUserId
14558
ParentId
14463902
PostTypeId
2
Score
1
ViewCount
0
LastEditorDisplayName
text
Body
First, let’s look at how the shell’s <code><(command)</code> command substitution works. The command is started with the output pointing to a newly created pipe. Then the pipe is passed on the command line as a filename to the outer command. For example: <pre><code>$ echo wc -w <(date) wc -l /dev/fd/63 </code></pre> Shows that the shell starts <code>date</code> with output to a pipe, and then passes the pseudofile <code>/dev/fd/63</code> referring to the new pipe at file descriptor 63 as the actual command line argument. <hr> To get the same behaviour in Python, we can implement the same thing: <pre><code>from subprocess import * date = Popen(['date'], stdout=PIPE) Popen(["wc", "-w", "/dev/fd/%d" % date.stdout.fileno()]) </code></pre> print <pre><code>6 /dev/fd/3 </code></pre> <hr> You could write a class to make it easier to do. This uses a <a href="http://www.python.org/dev/peps/pep-0343/" rel="nofollow"><code>with</code> statement</a> and temporarily keeps references to each spawned process, because otherwise the pipes would get closed when the process objects got garbage-collected. <pre><code>from subprocess import * class CommandSubstituter(object): def __init__(self): self._procs = [] def __enter__(self): return self def __exit__(self, *exc_info): pass def subst(self, *args, **kwargs): proc = Popen(*args, stdout=PIPE, **kwargs) self._procs.append(proc) return "/dev/fd/%d" % proc.stdout.fileno() with CommandSubstituter() as c: Popen(['wc', '-l', c.subst(['comm', '-12', c.subst(['sort', 'file1.txt']), c.subst(['sort', 'file2.txt'])])]) </code></pre>
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POuse subprocess.Popen to run a unix tool that requires multiple input redirects
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USandrewdotn
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POuse subprocess.Popen to run a unix tool that requires multiple input redirects
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTAcceptedByOriginator
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.