03-15-2007
Suppose that I don't have room in /usr for /usr/local but I do have some room in /export. So I make a directory called /export/usr.local and it has a subdirectory called bin. And I do a "ln -s /export/usr.local /usr/local". Now I do a "cd /usr/local" then I do a "cd bin". At this point my view is that I am in /usr/local/bin and a shell with a built-in pwd command may return that path. But /usr/bin/pwd will return /export/usr.local/bin. With more symbolic links in a path, there can be more aliases like this. The value returned by /usr/bin/pwd is the physical path. With good permissions on each directory leading to the current directory, /usr/bin/pwd can return the physical path. A built-in pwd in the same shell that navigated to the current directory may be able to return the particular logical path used to arrive at the current directory. Finding all logical paths to a particular directory would be rather daunting.
Writing a program like /usr/bin/pwd is not very easy in unix. You can stat the . directory to get the inode of the current directory. Then you can open .. and stat each file in the parent directory until you find the same inode. You walk up the chain one .. at a time repeating this process until . and .. are the same inode which means you have reached /. (Actually it is harder than that because you might traverse a mount point.) This is why putting an NFS mounted filesystem in / is very unwise... every /usr/bin/pwd must contact the NFS server to perform the stat.
10 More Discussions You Might Find Interesting
1. UNIX for Dummies Questions & Answers
Hi,
I have a file with about 60 lines of path:
app-defaults/boxXYZ.......
I want to change this to /my/path/goes/here/app-defaults/boxXYZ, but of course vi doesn't like the regualr :s/old/new/ command.
Is there any other quick way to do this?
Thanks ;) (2 Replies)
Discussion started by: Yinzer955i
2 Replies
2. UNIX for Dummies Questions & Answers
I'm having problems accessing the Knoppix software on my current computer and the replacement CD I ordered hasn't arrived yet.
I have a guess at what the answer would be for this question but I am not sure as I cannot test it with the software.
I have to create a directory called class, and... (1 Reply)
Discussion started by: mzero
1 Replies
3. Shell Programming and Scripting
suppose i ahve a shell script Nsdnet.sh inside a directory /dialp/Release/bin
another file nsdnet_file.csv is under the same directory. Now in the shell script i have call a java file, which reads the csvfile from the commandline.
Now when i run the file as
$ ./Nsdnet.sh ./nsdnet_file.csv
then... (5 Replies)
Discussion started by: priyanka3006
5 Replies
4. Shell Programming and Scripting
I have a script in which i want to print absolute path of the same script irrespective of path from where i run script.
I am using
test.sh:
echo "pwd : `pwd`"
echo "script name: $0"
echo "dirname: `dirname $0`"
when i run script from /my/test/dir/struct as ../test.sh the output i... (10 Replies)
Discussion started by: rss67
10 Replies
5. Shell Programming and Scripting
Hi,
I have a file abcd.txt which has contents in the form of full path file names i.e.
$home> vi abcd.txt
/a/b/c/r1.txt
/q/w/e/r2.txt
/z/x/c/r3.txt
Now I want to retrieve only the directory path name for each row
i.e
/a/b/c/
/q/w/e/
How to get the same through shell script?... (7 Replies)
Discussion started by: royzlife
7 Replies
6. Shell Programming and Scripting
/Path/snowbird9/nrfCompMgrRave1230100920.log.gz:09/20/2010 06:14:51 ERROR Error Message.
/Path/snowbird6/nrfCompMgrRave1220100920.log.gz:09/20/2010 06:14:51 ERROR Error Message.
/Path/snowbird14/nrfCompMgrRave920100920.log.gz:09/20/2010 06:14:51 ERROR Error Message.... (0 Replies)
Discussion started by: Shirisha
0 Replies
7. Shell Programming and Scripting
Hello,
I have a doubt:-
---------------------
Current script:-
################################################################################################
prefix=user@my-server:
find . -depth -type d -name .git -printf '%h\0' | while read -d "" path ; do (
cd "$path" || exit $?... (4 Replies)
Discussion started by: sahil_jammu
4 Replies
8. UNIX for Dummies Questions & Answers
Hello Everyone,
I want to convert
Relative Path - /home/stevin/data/APP_SERVICE/../datafile.txt
to
Absolute Path - /home/stevin/data/datafile.txt
Is there a built-in tool in Unix to do this or any good ideas as to how can I implement this.
-Steve (5 Replies)
Discussion started by: qwarentine
5 Replies
9. Shell Programming and Scripting
Hallo everyone,
I am running an SQL-Script over KShell-Script. Thus, in the KShell-Script there are these lines:
WORKPATH=$PWD/work
EXPORTDIR=export_meine_datei_bitte
EXPORTPATH=${WORKPATH}/${EXPORTDIR}
...
db2 connect to ${DBNAME} || die "can not open database connection"
db2... (9 Replies)
Discussion started by: ratnalein88
9 Replies
10. UNIX for Beginners Questions & Answers
Hello,
I am creating a file with all the source folders included in my git branch, when i grep for the used source, i found source included as relative path instead of absolute path, how can convert relative path to absolute path without changing directory to that folder and using readlink -f ? ... (4 Replies)
Discussion started by: Sekhar419
4 Replies
LEARN ABOUT DEBIAN
mojo::home
Mojo::Home(3pm) User Contributed Perl Documentation Mojo::Home(3pm)
NAME
Mojo::Home - Detect and access the project root directory in Mojo
SYNOPSIS
use Mojo::Home;
my $home = Mojo::Home->new;
$home->detect;
DESCRIPTION
Mojo::Home is a container for home directories.
ATTRIBUTES
Mojo::Home implements the following attributes.
"app_class"
my $class = $home->app_class;
$home = $home->app_class('Foo::Bar');
Application class.
METHODS
Mojo::Home inherits all methods from Mojo::Base and implements the following new ones.
"new"
my $home = Mojo::Home->new;
my $home = Mojo::Home->new('/home/sri/myapp');
Construct a new Mojo::Home object.
"detect"
$home = $home->detect;
$home = $home->detect('My::App');
Detect home directory from the value of the "MOJO_HOME" environment variable or application class.
"lib_dir"
my $path = $home->lib_dir;
Path to "lib" directory of application.
"list_files"
my $files = $home->list_files;
my $files = $home->list_files('foo/bar');
Portably list all files recursively in directory relative to the home diectory.
$home->rel_file($home->list_files('templates/layouts')->[1]);
"mojo_lib_dir"
my $path = $home->mojo_lib_dir;
Path to "lib" directory in which Mojolicious is installed.
"parse"
$home = $home->parse('/home/sri/myapp');
Parse home directory.
"rel_dir"
my $path = $home->rel_dir('foo/bar');
Portably generate an absolute path for a directory relative to the home directory.
"rel_file"
my $path = $home->rel_file('foo/bar.html');
Portably generate an absolute path for a file relative to the home directory.
"slurp_rel_file"
my $string = $home->slurp_rel_file('foo/bar.html');
Portably read all data at once from file relative to the home directory.
my $content = $home->slurp_rel_file($home->list_files('public')->[1]);
"to_string"
my $string = $home->to_string;
my $string = "$home";
Home directory.
SEE ALSO
Mojolicious, Mojolicious::Guides, <http://mojolicio.us>.
perl v5.14.2 2012-09-05 Mojo::Home(3pm)