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Top Forums Shell Programming and Scripting Use parameter expansion over a parameter expansion in bash. Post 303043406 by RavinderSingh13 on Tuesday 28th of January 2020 01:31:44 AM
Old 01-28-2020
Use parameter expansion over a parameter expansion in bash.

Hello All,

Could you please do help me here as I would like to perform parameter expansion in shell over a parameter expansion.

Let's say I have following variable.
Code:
path="/var/talend/nat/cdc"

Now to get only nat I could do following.
Code:
path1="${path%/*}"
path1="${path1##*/}"

Here in this approach I am creating a temporary variable path1 and again performing parameter expansion, how about if I want to perform this in single time without having temporary variable? I have tried it like:

Code:
echo "${((${path%/*}))##*/}"

Which is giving me an error. Any help, guidance is appreciated.

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
 

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link(2) 							System Calls Manual							   link(2)

NAME
link() - link to a file SYNOPSIS
DESCRIPTION
The system call creates a new link (directory entry) for the existing file. path1 points to a path name naming an existing file. path2 points to a path name naming the new directory entry to be created. RETURN VALUE
Upon successful completion, returns zero. Otherwise, it returns -1 and sets (see errno(2)) to indicate the error. ERRORS
The system call fails and no link is created if one or more of the following is true: A component of either path prefix denies search permission. The requested link requires writing in a directory that does not permit writing. The user's or group's disk quota block limit has been reached for this file system. The link named by path2 exists. path points outside the allocated address space of the process. The reliable detection of this error is implementation dependent. Too many symbolic links were encountered in translating either path name. The maximum number of links to a file would be exceeded. Either the specified path exceeds bytes, or a component of either specified path exceeds while is in effect. The file named by path1 does not exist. A component of either path prefix does not exist. path2 points to a null path name. path1 or path2 is null. The directory to contain the file cannot be extended. A component of either path prefix is not a directory. The file named by path1 is a directory and the effective user ID is not a user who has appropriate privileges. Some file systems return this error whenever path1 names a directory, regardless of the user ID. The requested link requires writing in a directory on a read-only file system. The link named by path2 and the file named by path1 are on different logical devices (file systems). SEE ALSO
cp(1), link(1M), symlink(2), unlink(2), symlink(4), privileges(5). STANDARDS CONFORMANCE
link(2)
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