![]() ![]() Useful if the program you are piping to or from requires extra information before it starts, such as piping data to gpg which requires a passphrase before data is processed. Wait until the first byte is transferred before showing any progress information or calculating any ETAs. The following options affect what information is output by pv. This option can be useful if you are using -L and all you want to do is limit the transfer rate of the pipe. If combined with -timer, then each output line is prefixed with the elapsed time in seconds. If combined with -line-mode, then instead of bytes of a percentage, the number of lines so far is shown. NOTE: If combined with -bytes, this option causes the number of bytes processed to be shown, instead of a percentage. Instead of giving a visual indication of progress, pv gives an integer percentage, one per line on standard error, suitable for piping. For more information, see the Formatting section below. Ignore the options -p, -t, -e, -r, -a, -b, -T, and -A, and instead use the format string FORMAT to determine the output format. For more information, see % n A in the Formatting section below. For more information, see %T in the Formatting section below. Turn on the transfer buffer percentage display, showing the percentage of the transfer buffer in use. ![]() Turn on the total byte counter, displaying the total amount of data transferred so far. Turn on the average rate counter, displaying the current rate of data transfer. Turn on the rate counter, displaying the current throughput rate. When the estimated time is more than 6 hours in the future, the date is also shown. Turn on the ETA timer, but display the estimated local time of arrival instead of time left. (If you want an ETA when piping from standard input, specify the size with -s.) This option has no effect if the total data size cannot be determined. This attempts to guess, based on previous transfer rates and the total data size, how long before completion. Turn on the timer, displaying the total elapsed time pv has run. If standard input is not a file, and no size is given (with the -s modifier), the progress bar cannot indicate how close to completion the transfer is, so it moves left and right to indicate that data is moving. If no display switches are specified, pv behaves as if -p, -t, -e, -r, and -b were specified (everything except average rate is switched on, by default). The following options control how information is output by pv. Note that if a parameter is included with a long option name, such as -last-written NUM, the same parameter should be specified with the corresponding short option, such as -A NUM. ![]() The following is the general syntax of the pv command. However, other commands might take a long time, and it would be helpful to know when they might finish. In the pipeline example above, the results are shown almost instantly, so you would not need to monitor the progress. ![]() The example above shows how the output of one command can be piped to other commands in a series, called a pipeline. cat myfile.txt | grep meeting | grep Monday | \ It then extracts dates of those meetings using a Perl regular expression. For example, the following command extracts lines about meetings, then extracts only the lines about meetings happening on a Monday. This new output can be piped to sed to modify the output. You can pipe the output to grep to filter it: cat myfile.txt | grep meeting The ABC meeting is on Monday, October 4. Maybe you want to extract only the lines that have the word "meeting" included. You can use that output as input to another program. The GHI meeting is on Monday, December 12. The DEF meeting is on Tuesday, November 8. The 123 conference is on Friday, August 12. For example, if you want to read the contents of a text file and send it to standard output (the terminal screen), you can use the cat command: cat myfile.txt Using the command line, you can " pipe" the output of one command to the input of another command using the vertical bar (" |"), or pipe, symbol. ETA (estimated time of arrival) of when the operation is expected to be complete.Percentage complete, with progress bar.The information displayed by pv includes: The pv ("pipe viewer") program watches data flow through a pipeline, and displays information about its progress. ![]()
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