transfer a URL
(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
(SSL) This option explicitly allows curl to perform "insecure" SSL connections and transfers. All
SSL connections are attempted to be made secure by using the CA certificate bundle installed by
default. This makes all connections considered "insecure" fail unless -k, --insecure is used.
See this online resource for further details: http://curl.haxx.se/docs/sslcerts.html
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).
print lines matching a pattern
Context Line Control
-A NUM, --after-context=NUM
Print NUM lines of trailing context after matching lines. Places a line containing a group
separator (--) between contiguous groups of matches. With the -o or --only-matching option, this
has no effect and a warning is given.
Prefix each line of output with the 1-based line number within its input file. (-n is specified
grep searches the named input FILEs (or standard input if no files are named, or if a single hyphen-minus
(-) is given as file name) for lines containing a match to the given PATTERN. By default, grep prints
the matching lines.
Before a command is executed, its input and output may be redirected using a special notation interpreted
by the shell. Redirection may also be used to open and close files for the current shell execution
environment. The following redirection operators may precede or appear anywhere within a simple command
or may follow a command. Redirections are processed in the order they appear, from left to right.
Redirection of output causes the file whose name results from the expansion of word to be opened for
writing on file descriptor n, or the standard output (file descriptor 1) if n is not specified. If the
file does not exist it is created; if it does exist it is truncated to zero size.
The general format for redirecting output is:
If the redirection operator is >, and the noclobber option to the set builtin has been enabled, the
redirection will fail if the file whose name results from the expansion of word exists and is a regular
file. If the redirection operator is >|, or the redirection operator is > and the noclobber option to
the set builtin command is not enabled, the redirection is attempted even if the file named by word