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Top Forums UNIX for Dummies Questions & Answers How to get nth line from a file usuing commands Post 302240624 by radoulov on Friday 26th of September 2008 06:50:52 AM
Old 09-26-2008
Or:

Code:
sed '789!d;q' infile

A quick test:

Code:
$ time head -813000 alert_xxx.log | tail -1
Starting control autobackup

real    0m5.457s
user    0m1.110s
sys     0m6.710s
$ time sed '813000!d;q' alert_xxx.log
Starting control autobackup

real    0m0.721s
user    0m0.470s
sys     0m0.200s

 

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break(1)							   User Commands							  break(1)

NAME
break, continue - shell built-in functions to escape from or advance within a controlling while, for, foreach, or until loop SYNOPSIS
sh break [n] continue [n] csh break continue ksh *break [n] *continue [n] ksh93 +break [n] +continue [n] DESCRIPTION
sh The break utility exits from the enclosing for or while loop, if any. If n is specified, break n levels. The continue utility resumes the next iteration of the enclosing for or while loop. If n is specified, resume at the n-th enclosing loop. csh The break utility resumes execution after the end of the nearest enclosing foreach or while loop. The remaining commands on the current line are executed. This allows multilevel breaks to be written as a list of break commands, all on one line. The continue utility continues execution of the next iteration of the nearest enclosing while or foreach loop. ksh The break utility exits from the enclosed for, while, until, or select loop, if any. If n is specified, then break n levels. If n is greater than the number of enclosing loops, the outermost enclosing loop shall be exited. The continue utility resumes the next iteration of the enclosed for, while, until, or select loop. If n is specified then resume at the n- th enclosed loop. If n is greater than the number of enclosing loops, the outermost enclosing loop shall be used. On this manual page, ksh(1) commands that are preceded by one or two * (asterisks) are treated specially in the following ways: 1. Variable assignment lists preceding the command remain in effect when the command completes. 2. I/O redirections are processed after variable assignments. 3. Errors cause a script that contains them to abort. 4. Words that follow a command preceded by ** that are in the format of a variable assignment are expanded with the same rules as a variable assignment. This means that tilde substitution is performed after the = sign, and also that word splitting and file name generation are not performed. ksh93 break is a shell special built-in that exits the smallest enclosing for, select, while, or until loop. It also exits the nth enclosing loop if n is specified. Execution continues at the command following the loop or loops. If n is specified, it must be a positive integer >=1. If n is larger than the number of enclosing loops, the last enclosing loop is exited. continue is a shell special built-in that continues execution at the top of the smallest enclosing for, select, while, or until loop, if any; or of the top of the nth enclosing loop if n is specified. If n is specified, it must be a positive integer >=1. If n is larger than the number of enclosing loops, the last enclosing loop is used. On this manual page, ksh93(1) commands that are preceded by one or two + symbols are special built-in commands and are treated the follow- ing ways: 1. Variable assignment lists preceding the command remain in effect when the command completes. 2. I/O redirections are processed after variable assignments. 3. Errors cause a script that contains them to abort. 4. Built-in commands are not valid function names. 5. Words following a command preceded by ++ that are in the format of a variable assignment are expanded with rules as a variable assignment. This means that tilde substitution is performed after the = sign and field splitting and file name generation are not performed. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Availability |SUNWcsu | +-----------------------------+-----------------------------+ SEE ALSO
csh(1), exit(1), ksh(1), ksh93(1), sh(1), attributes(5) SunOS 5.11 8 Apr 2008 break(1)
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