If there are more input sources, each input source will be separated, but the columns from each input source will be linked see --link.
GNU parallel will try pzstd , lbzip2 , pbzip2 , zstd , pigz , lz4 , lzop , plzip , lzip , lrz , gzip , pxz , lzma , bzip2 , xz , clzip , in that order, and use the first available. If you append 'auto' to mytime e. This is tested on ash , bash , dash , ksh , sh , and zsh. In Bash var can also be a Bash function - just remember to export -f the function, see command. The estimate is based on the runtime of finished jobs, so the first estimate will only be shown when the first job has finished.
With --tmux and --tmuxpane GNU parallel will start tmux in the foreground. With --semaphore GNU parallel will run the command in the foreground opposite --bg , and wait for completion of the command before exiting.
For performance reasons, this check is performed only at the start and every time --sshloginfile is changed. If an host goes down after the first check, it will go undetected until --sshloginfile is changed; --retries can be used to mitigate this. This will likely be fixed in a later release. This takes in the order of 0.
It can be disabled with -u , but this means output from different commands can get mixed. For --pipe bytes transferred and bytes returned are number of input and output of bytes. If used with --onall or --nonall the output will grouped by sshlogin in sorted order. If used with --pipe --roundrobin and the same input, the jobslots will get the same blocks in the same order in every run. When used otherwise: Use at most recsize nonblank input lines per command line.
Trailing blanks cause an input line to be logically continued on the next input line. When used otherwise: Synonym for the -L option. Unlike -L , the recsize argument is optional. If recsize is not specified, it defaults to one. Normally --line-buffer does not buffer on disk, and can thus process an infinite amount of data, but it will buffer on disk when combined with: --keep-order , --results , --compress , and --files. This will make it as slow as --group and will limit output to the available disk space.
With --keep-order --line-buffer will output lines from the first job continuously while it is running, then lines from the second job while that is running. It will buffer full lines, but jobs will not mix. Arguments will be recycled if one input source has more arguments than the others:. See also -X for context replace. If in doubt use -X as that will most likely do what is needed. If less than size bytes are free, no more jobs will be started.
If the available memory falls below size , only one job will be running. If a single job takes up at most size RAM, all jobs will complete without running out of memory. If you have swap available, you can usually lower size to around half the size of a single job - with the slight risk of swapping a little. Jobs will be resumed when more RAM is available - typically when the oldest job completes. This is useful for scripts that depend on features only available from a certain version of GNU parallel.
When used with --pipe -N is the number of records to read. This is somewhat slower than --block. This is useful for running the same command e. When using --group the output will be grouped by each server, so all the output from one server will be grouped together. The block size is determined by --block. The block read will have the final partial record removed before the block is passed on to the job.
The partial record will be prepended to next block. If both --recstart and --recend are given both will have to match to find a split position. To have no record separator use --recend "". If performance is important use --pipepart.
See also: --recstart , --recend , --fifo , --cat , --pipepart , --files. If using a block device with lot of NUL bytes, remember to set --recend ''. The content of the input sources must be the same and the arguments must be unique. The following dynamic replacement strings are also activated.
They are inspired by bash's parameter expansion:. By default GNU parallel will run jobs at the same nice level as GNU parallel is started - both on the local machine and remote servers, so you are unlikely to ever use this option.
Setting --nice will override this nice level. If the nice level is smaller than the current nice level, it will only affect remote jobs e. Another useful setting is ,,,, which would make both parenthesis ,, :. You can give multiple profiles by repeating --profile. If parts of the profiles conflict, the later ones will be used. Most people will not need this. Quoting is disabled by default.
The swap activity is only sampled every 10 seconds as the sampling takes 1 second to do. If --recend is given endstring will be used to split at record end. If both --recstart and --recend are given the combined string endstring startstring will have to match to find a split position. This is useful if either startstring or endstring match in the middle of a record. Use --regexp to interpret --recstart and --recend as regular expressions. This is slow, however. If name does not contain replacement strings and does not end in.
If name ends in. Standard error will be stored in the same file name with '. See also: --joblog , --results , --resume-failed , --retries.
See also: --joblog , --resume , --retry-failed , --retries. If the Seq is run, it will not be run again. So if needed, you can change the command for the seqs not run yet:.
Again this means you can change the command, but not the arguments. It will run the failed seqs and the seqs not yet run:. It ignores any arguments or commands given on the command line:. See also: --joblog , --resume , --resume-failed , --retries.
You can have dynamic replacement strings by including parenthesis in the replacement string and adding a regular expression between the parenthesis. The default normally works as expected when used interactively, but when used in a script name should be set.
There are many limitations of shebang! Multiple --shellquote with quote the string multiple times, so parallel --shellquote parallel --shellquote can be written as parallel --shellquote --shellquote. One or more --sqlworker must be run to actually execute the jobs. If --wait is set, GNU parallel will wait for the jobs to complete. If --sqlworker runs on the local machine, the hostname in the SQL table will not be ':' but instead the hostname of the machine.
If hostgroups is given, the sshlogin will be added to that hostgroup. The sshlogin will always be added to a hostgroup named the same as sshlogin. If only the hostgroup is given, only the sshlogins in that hostgroup will be used.
Multiple hostgroup can be given. GNU parallel will determine the number of CPUs on the remote computers and run the number of jobs as specified by -j. Normally ncpus will not be needed. The sshlogin must not require a password ssh-agent , ssh-copy-id , and sshpass may help with that.
The sshlogin ':' is special, it means 'no ssh' and will therefore run on the local computer. The sshlogin '.. The sshlogin '-' is special, too, it read sshlogins from stdin standard input. To specify more sshlogins separate the sshlogins by comma, newline in the same string , or repeat the options multiple times.
The sshloginfile '.. The sshloginfile '. The sshloginfile '-' is special, too, it read sshlogins from stdin standard input. If the sshloginfile is changed it will be re-read when a job finishes though at most once per second. This makes it possible to add and remove hosts while running. This can be used to have a daemon that updates the sshloginfile to only contain servers that are up:.
Using --tty unfortunately means that GNU parallel cannot kill the jobs with --timeout , --memfree , or --halt. This is due to GNU parallel giving each child its own process group, which is then killed. Process groups are dependant on the tty.
GNU parallel detects if a process dies before the waiting time is up. Thus these are equivalent: --timeout and --timeout 1d3. It also disables --tag. GNU parallel outputs faster with -u. Compare the speeds of these:. With --use-sockets-instead-of-threads or --use-cores-instead-of-threads you can force it to be computed as the number of filled sockets or number of cores instead.
Use -v -v to print the wrapping ssh command when running remotely. Files transferred using --transferfile and --return will be relative to mydir on remote computers. The special mydir value If --cleanup is given these dirs will be removed.
The special mydir value. If the current working dir is beneath your home dir, the value. This means that if your home dir is different on remote computers e.
If the file names may contain a newline use With GNU parallel you can build a simple network scanner to see which addresses respond to ping :. GNU parallel can take the arguments from command line instead of stdin standard input.
To compress all html files in the current dir using gzip run:. This will run mv for each file. It can be done faster if mv gets as many arguments that will fit on the line:. The first will run rm times, while the last will only run rm as many times needed to keep the command line length short enough to avoid Argument list too long it typically runs times. This will also only run rm as many times needed to keep the command line length short enough.
This will run with number-of-cpus jobs in parallel for all jpg files in a directory:. The command will generate files like. This command will make files like. Another solution is to quote the whole command:. A job can consist of several commands. This will print the number of files in each directory:. Print the line number and the URL. Create a mirror directory with the same filenames except all files and symlinks are empty files.
You have a bunch of file. You want them sorted into dirs. The dir of each file should be named the first letter of the file name. You have a dir with files named as 24 hours in 5 minute intervals: , , You want to find the files missing:. If the composed command is longer than a line, it becomes hard to read. In Bash you can use functions. Just remember to export -f the function. To do this on remote servers you need to transfer the function using --env :.
If your environment aliases, variables, and functions is small you can copy the full environment without having to export -f anything. This shows the most recent output line until a job finishes.
After which the output of the job is printed in full:. Log rotation renames a logfile to an extension with a higher number: log. The oldest log is removed. Rely on your manufacturer's OEM stuff Most computer manufacturers nowadays set apart one or even two partitions to store service and recovery data.
If you are an experienced user and still have not reinstalled the OS on your own , you most likely do not need these files and can remove the partitions in order to make room for Debian. However, you do this at your own risk. Always defragment and chkdsk the filesystem in Windows before trying and be sure to have up to date backup copies of your data. Special configuration issues Wifi not available in Windows after installing Debian If your wifi interface is not available in Windows after you installed and booted Debian, this is due to a bug in the Windows driver of your card.
For example, Atheros chipsets are known to not power up correctly if not having been powered down by the same Windows driver beforehand. Seizure warnings Photosensitive seizure warning. Report this product Report this app to Microsoft Thanks for reporting your concern. Our team will review it and, if necessary, take action. Sign in to report this app to Microsoft.
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