fish-common 2.2.0-3 / usr / share / fish / man / man1 / psub.1

.TH "psub" 1 "Wed Dec 16 2015" "Version 2.2.0" "fish" \" -*- nroff -*-
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.SH NAME
\fBpsub\fP -- perform process substitution 

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.SS "Synopsis"
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COMMAND1 ( COMMAND2 | \fBpsub\fP [-f] )
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.SS "Description"
Posix shells feature a syntax that is a mix between command substitution and piping, called process substitution\&. It is used to send the output of a command into the calling command, much like command substitution, but with the difference that the output is not sent through commandline arguments but through a named pipe, with the filename of the named pipe sent as an argument to the calling program\&. \fCpsub\fP combined with a regular command substitution provides the same functionality\&.
.PP
If the \fC-f\fP or \fC--file\fP switch is given to \fCpsub\fP, \fCpsub\fP will use a regular file instead of a named pipe to communicate with the calling process\&. This will cause \fCpsub\fP to be significantly slower when large amounts of data are involved, but has the advantage that the reading process can seek in the stream\&.
.SS "Example"
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\fBdiff\fP (\fBsort\fP a\&.txt | \fBpsub\fP) (\fBsort\fP b\&.txt | \fBpsub\fP)
  shows the difference between the sorted versions of files `a\&.txt` and `b\&.txt`\&.
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