Linux – Cut and Awk command : Delimiter behaviour

awklinux

I tried to use cut command to get a list of file names and their sizes from "ls -l" command output.

$ ls -l | cut -f 5,9 -d " "

It gives me output based on 'SINGLE WHITE SPACE' as a delimiter. When "ls -l" output contains consecutive spaces in certain rows, then the output of the command is not proper for those rows.
The rows which have only single white space as column separator, give correct output.

When I run following command:

$ ls -l | awk '{ print $5"\t"$9 }'

awk is ignoring multiple spaces and properly extracting columns from "ls -l" output.
While, cut is treating each space as a delimiter, there by putting values in wrong columns.

It gives correct output for all rows.

Why is this happening ? What can I do to work this out with cut command ?

Best Answer

awk splits fields on whitespace. cut splits fields on a delimiting character. awk is the better tool for this problem.

As an alternative, you can pipe ls -l into a utility that either compresses multiple space chars (maybe tr -s), or into a utility that replaces multiple space chars with a single one (maybe sed). Then cut will do what you want it to.

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find /home/www \( -type d -name .git -prune \) -o -type f -print0 | xargs -0 sed -i 's/subdomainA\.example\.com/subdomainB.example.com/g'

-print0 tells find to print each of the results separated by a null character, rather than a new line. In the unlikely event that your directory has files with newlines in the names, this still lets xargs work on the correct filenames.

\( -type d -name .git -prune \) is an expression which completely skips over all directories named .git. You could easily expand it, if you use SVN or have other folders you want to preserve -- just match against more names. It's roughly equivalent to -not -path .git, but more efficient, because rather than checking every file in the directory, it skips it entirely. The -o after it is required because of how -prune actually works.

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Linux – How to change permissions for a folder and its subfolders/files in one step

The other answers are correct, in that chmod -R 755 will set these permissions to all files and subfolders in the tree. But why on earth would you want to? It might make sense for the directories, but why set the execute bit on all the files?

I suspect what you really want to do is set the directories to 755 and either leave the files alone or set them to 644. For this, you can use the find command. For example:

To change all the directories to 755 (drwxr-xr-x):

find /opt/lampp/htdocs -type d -exec chmod 755 {} \;

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Some splainin': ^{(thanks @tobbez)}

chmod 755 {} specifies the command that will be executed by find for each directory
chmod 644 {} specifies the command that will be executed by find for each file
{} is replaced by the path
; the semicolon tells find that this is the end of the command it's supposed to execute
\; the semicolon is escaped, otherwise it would be interpreted by the shell instead of find

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Bash – How to do a recursive find/replace of a string with awk or sed

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