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Top Forums Shell Programming and Scripting Bash script search, improve performance with large files Post 303033020 by Peasant on Thursday 28th of March 2019 12:40:10 PM
Old 03-28-2019
When processing extremely large files you might consider using split first.
Then in multicore environments spawn several awks or greps to process it in parallel from shell script.
There are also GNU tools which offer parallelism without shell logic.

Should be a bit tougher to program, but processing time will be reduced significantly if you have cores and disks are fast to service.

Memory also comes in play, since split will read the files, and operating system will cache those files in memory, if the same is available.
Making those awks or greps processes much faster on read operations.

Of course, limit being free memory on the system and configuration of the file system caching in general.
In default configurations file system caching will be able to use a large portion free memory on most linux / unix systems i've seen.

Hope that helps
Regards
Peasant.
 

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RBASH(1)						      General Commands Manual							  RBASH(1)

NAME
rbash - restricted bash, see bash(1) RESTRICTED SHELL
If bash is started with the name rbash, or the -r option is supplied at invocation, the shell becomes restricted. A restricted shell is used to set up an environment more controlled than the standard shell. It behaves identically to bash with the exception that the follow- ing are disallowed or not performed: o changing directories with cd o setting or unsetting the values of SHELL, PATH, ENV, or BASH_ENV o specifying command names containing / o specifying a filename containing a / as an argument to the . builtin command o specifying a filename containing a slash as an argument to the -p option to the hash builtin command o importing function definitions from the shell environment at startup o parsing the value of SHELLOPTS from the shell environment at startup o redirecting output using the >, >|, <>, >&, &>, and >> redirection operators o using the exec builtin command to replace the shell with another command o adding or deleting builtin commands with the -f and -d options to the enable builtin command o using the enable builtin command to enable disabled shell builtins o specifying the -p option to the command builtin command o turning off restricted mode with set +r or set +o restricted. These restrictions are enforced after any startup files are read. When a command that is found to be a shell script is executed, rbash turns off any restrictions in the shell spawned to execute the script. SEE ALSO
bash(1) GNU Bash-4.0 2004 Apr 20 RBASH(1)
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