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Created by Dr. Xi on August 13, 2012 14:54:44    Last update: August 13, 2012 14:54:44
According to wikipedia , only two characters are invalid in a file name: In Unix-like file systems the null character, as that is the end-of-string indicator and the path separator / are prohibited.
Created by Dr. Xi on February 28, 2011 12:29:19    Last update: February 28, 2011 12:30:40
The Unix shell passes these parameters to the shell script: Variable Meaning $* A single string representing all command line arguments separated by $IFS (internal field separator, usually a space) $@ A sequence of strings representing the command line arguments. $1,$2...$n $1 is the first argument, $2 is the second argument, and so on... $0 The name of the script itself. $# The number of arguments. Example shell script ( ): #!/bin/sh echo $# arguments passed to $0: $@ ... Output for ./ "a b c d" : 1 arguments passed to ./ a b c d here ... Output for ./ a "b c" d : 3 arguments passed to ./ a b c d here ...
Created by Dr. Xi on December 04, 2009 04:33:05    Last update: December 04, 2009 04:33:05
Variable Meaning $_ The default or implicit variable. @_ Within a subroutine the array @_ contains the parameters passed to that subroutine. $a, $b Special package variables when using sort() $<digit> Contains the subpattern from the corresponding set of capturing parentheses from the last pattern match, not counting patterns matched in nested blocks that have been exited already. $. Current line number for the last filehandle accessed. $/ The input record separator, newline by default. $| If set to nonzero, forces a flush right away and after every write or print on the currently selected output channel. Default is 0 (regardless of whether the channel is really buffered by the system or not; $| tells you only whether you've asked Perl explicitly to flush after...
Created by Dr. Xi on September 29, 2008 23:05:12    Last update: September 29, 2008 23:06:16
These variables are set or used by the Unix shell to modify its behavior. Variable Description ENV=file Name of script that gets executed at startup; Usually, ENV=$HOME/.kshrc FCEDIT=file Editor used by fc (fix command) command. If $FCEDIT is not defined, use $EDITOR, otherwise use the default (vi or ed). FPATH=dirs Directories to search for function definitions; undefined functions are set via typeset -fu . FPATH is searched when these functions are first referenced. HISTFILE=file File in which to store command history. Default is $HOME/.sh_history for Korn shell, $HOME/.bash_history for Bash. If not set, history is lost after logout. HISTSIZE=n Max number of commands to keep in history. HOME=dir Home directory; set by login from passwd file. IFS='chars' Internal field separators. Default is space, tab, and...