(HTTP) Fail silently (no output at all) on server errors. This is mostly done to better enable
scripts etc to better deal with failed attempts. In normal cases when a HTTP server fails to
deliver a document, it returns an HTML document stating so (which often also describes why and
more). This flag will prevent curl from outputting that and return error 22.
This method is not fail-safe and there are occasions where non-successful response codes will slip
through, especially when authentication is involved (response codes 401 and 407).
(HTTP/HTTPS) If the server reports that the requested page has moved to a different location
(indicated with a Location: header and a 3XX response code), this option will make curl redo the
request on the new place. If used together with -i, --include or -I, --head, headers from all
requested pages will be shown. When authentication is used, curl only sends its credentials to the
initial host. If a redirect takes curl to a different host, it won't be able to intercept the
user+password. See also --location-trusted on how to change this. You can limit the amount of
redirects to follow by using the --max-redirs option.
When curl follows a redirect and the request is not a plain GET (for example POST or PUT), it will
do the following request with a GET if the HTTP response was 301, 302, or 303. If the response
code was any other 3xx code, curl will re-send the following request using the same unmodified
A pipeline is a sequence of one or more commands separated by one of the control operators | or |&. The
format for a pipeline is:
[time [-p]] [ ! ] command [ [|⎪|&] command2 ... ]
The standard output of command is connected via a pipe to the standard input of command2. This
connection is performed before any redirections specified by the command (see REDIRECTION below). If |&
is used, the standard error of command is connected to command2's standard input through the pipe; it is
shorthand for 2>&1 |. This implicit redirection of the standard error is performed after any
redirections specified by the command.
The return status of a pipeline is the exit status of the last command, unless the pipefail option is
enabled. If pipefail is enabled, the pipeline's return status is the value of the last (rightmost)
command to exit with a non-zero status, or zero if all commands exit successfully. If the reserved word
! precedes a pipeline, the exit status of that pipeline is the logical negation of the exit status as
described above. The shell waits for all commands in the pipeline to terminate before returning a value.
If the time reserved word precedes a pipeline, the elapsed as well as user and system time consumed by
its execution are reported when the pipeline terminates. The -p option changes the output format to that
specified by POSIX. When the shell is in posix mode, it does not recognize time as a reserved word if
the next token begins with a `-'. The TIMEFORMAT variable may be set to a format string that specifies
how the timing information should be displayed; see the description of TIMEFORMAT under Shell Variables
When the shell is in posix mode, time may be followed by a newline. In this case, the shell displays the
total user and system time consumed by the shell and its children. The TIMEFORMAT variable may be used
to specify the format of the time information.
Each command in a pipeline is executed as a separate process (i.e., in a subshell).
If no -f option is specified, the first operand to awk shall be the text of the awk program. The
application shall supply the program operand as a single argument to awk. If the text does not end
in a <newline>, awk shall interpret the text as if it did.
Either of the following two types of argument can be intermixed:
A pathname of a file that contains the input to be read, which is matched against the set of
patterns in the program. If no file operands are specified, or if a file operand is '-' , the
standard input shall be used.
An operand that begins with an underscore or alphabetic character from the portable character set
(see the table in the Base Definitions volume of IEEE Std 1003.1-2001, Section 6.1, Portable
Character Set), followed by a sequence of underscores, digits, and alphabetics from the portable
character set, followed by the '=' character, shall specify a variable assignment rather than a
pathname. The characters before the '=' represent the name of an awk variable; if that name is an
awk reserved word (see Grammar ) the behavior is undefined. The characters following the equal
sign shall be interpreted as if they appeared in the awk program preceded and followed by a
double-quote ( ' )' character, as a STRING token (see Grammar ), except that if the last character
is an unescaped backslash, it shall be interpreted as a literal backslash rather than as the first
character of the sequence "\"" . The variable shall be assigned the value of that STRING token
and, if appropriate, shall be considered a numeric string (see Expressions in awk ), the variable
shall also be assigned its numeric value. Each such variable assignment shall occur just prior to
the processing of the following file, if any. Thus, an assignment before the first file argument
shall be executed after the BEGIN actions (if any), while an assignment after the last file
argument shall occur before the END actions (if any). If there are no file arguments, assignments
shall be executed before processing the standard input.