What constitutes internal commands from external commands?
Nothing tricky about it. External commands are external because they're external -- they're files, programs the shell runs. They exist whether you're running a shell or not. cd is a pure builtin, without any external equivalent -- by definition cd must be a builtin, it wouldn't work.
ls on the other hand is not a builtin -- it has binary executables and manual pages and stuff.
printf is both -- it is a builtin in most shells, for performance reasons since it's used often for tiny tasks. But the binary program also exists in case it's needed.
An extreme case is the busybox shell, which is intended to be a mini stand-alone UNIX system. It may have hundreds of builtins, including minimal versions of things like awk, sed, cp, mv, xargs, etc etc etc -- which traditionally have never been builtins.
So, the reason all these programs seem identical between shells is because your shell doesn't contain the universe, just talks to it.
what does this symbol ~ represent in unix for example....
If i create directories called personal and lab and lab5 and the command chmod 776~/lab5 is issued. What results would i expect to get. basically i know that chmod 776 would prevent others from executing the files in the directory but... (2 Replies)
Hi ,
i have few doubts about the braces and spaces which are quite often used:
for instance:
when i try the belo command it will not work
export variable= cat filename
rather when i try the cat command without any space it works fine
export variable=cat filename
and... (3 Replies)
Many scripts are executed in the following way.
. /scriptname
Even when the file does not have execute permission, it can be executed this way. How does this work? (6 Replies)
Hi,
I am a newbie in unix shell scripting and I am trying to understand the result of the following line :
ls -l $1*$4*ready
I understand the ls-l but the rest is just really confusing. Any help would be appreciated.
TIA (3 Replies)
this post is related to the arrangements of libraries in a solaris-8 distribution.
i want to build external packages on solaris-8
i need to know why libraries are scattered in a solaris distribution among different below mentioned directories,
please tell me whats the importance ??
/lib... (3 Replies)
Hello... I am getting ready to create a bunch of groups for several of our servers all of which are running Aix 5.3. We really want to keep people away from using the root login and as such the systems have been hardened using aixpert and if it is absolutely needed people must su -.
There are... (1 Reply)
What is the significance of the forward slash(/) while specifying a directory?
cp -av /dir/ /opt/
and
cp -av /dir /opt
Does effectively the same job it seems? (2 Replies)
Hi
I was trying to understand what ':-' means when used with variables
echo ${x:-10}
if
Thanks (4 Replies)
Discussion started by: zulfi123786
4 Replies
LEARN ABOUT DEBIAN
surfraw-update-path
SURFRAW-UPDATE-PATH(1) User Contributed Perl Documentation SURFRAW-UPDATE-PATH(1)NAME
surfraw-update-path - updates PATH in shell config files
SYNOPSIS
surfraw-update-path [-add] [-remove] [-check] [-sys] [-all] [-help] [-shell=SHELL]
DESCRIPTION
surfraw-update-path adds the surfraw elvi directory (/usr/lib/surfraw) to your PATH in your shell's config file.
Currently it supports bash, sh, csh, tcsh, ash, dash, ksh, pdksh, zsh, rc, and es
Don't forget to login again or source your login files for it to take effect.
OPTIONS -check
Checks to see if the surfraw config code is present. This is the default.
-add
Adds the surfraw config code.
-remove
Removes the surfraw config code
-sys
Updates the system-wide shell config instead of the user. Must be done as root.
-shell=SHELL
Selects the shell to configure. Defaults to the value of the $SHELL environment variable.
Currently supported shells are:
sh, ash, bash, dash, csh, tcsh, ksh, pdksh, zsh, rc, and es.
-all
Attempts to configure the startup files for all known shells
-help
Gives a usage message
RETURN VALUE -check returns 0 if the surfraw code is present in the file, 1 if it is not found, or 2 on error.
All other options return 0 on success, or 2 on error.
ENVIRONMENT
SHELL
Used to determine which shell to configure, if -shell is not given.
HOME
Used to find users config files.
ENV Used by posix-compliant shells to specify a startup rc file.
ZDOTDIR
Used to find user config files for zsh. If not set, defaults to HOME.
SEE ALSO surfraw(1), sh(1), ash(1), bash(1), dash(1), csh(1), tcsh(1), ksh(1), pdksh(1), zsh(1), rc(1), es(1)AUTHOR
Ian Beckwith <ianb@erislabs.net>
perl v5.12.4 2011-07-12 SURFRAW-UPDATE-PATH(1)