Gawk/Naming-Standard-Input
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2.4 Naming Standard Input
Often, you may wish to read standard input together with other files. For example, you may wish to read one file, read standard input coming from a pipe, and then read another file.
The way to name the standard input, with all versions of awk
,
is to use a single, standalone minus sign or dash, ‘-
’. For example:
some_command | awk -f myprog.awk file1 - file2
Here, awk
first reads file1
, then it reads
the output of some_command
, and finally it reads
file2
.
You may also use "-"
to name standard input when reading
files with getline
(see section Using getline
from a File).
And, you can even use "-"
with the -f
option
to read program source code from standard input (see section Command-Line Options).
In addition, gawk
allows you to specify the special
file name /dev/stdin
, both on the command line and
with getline
.
Some other versions of awk
also support this, but it
is not standard.
(Some operating systems provide a /dev/stdin
file
in the filesystem; however, gawk
always processes
this file name itself.)