File management

Finding or searching through files and folders

Search for a string

A case-sensitive search through all of the files from current folder and below.

$ find . | xargs grep -s "mystring" | more

A case-insensitive search through all of the files from current folder and below.

$ find . | xargs grep -si "mystring" | more

A case-insensitive search through all of the files from current folder and below, and truncate long search results.

$ find . | xargs grep -sioE ".{0,20}mystring.{0,20}" | more

An alternative way to search for keywords.

$ cat file.txt | grep word
$ grep -r -e word /etc"

Copy including hidden files

• Last tested on Ubuntu 14.04.2 LTS (trusty)

$ cp -r folder1/. target/

Delete files

Delete files recursively

• Lasted tested on Ubuntu 16.04.2 LTS (xenial)

$ find . -type f -name "*.mp4" -exec rm {} \;

Fastest way to delete a folder

• Last tested on RHEL 8.3 (2021-03-09)

$ mkdir empty
$ rsync -a --delete empty/ foldername

Setting a default group for a folder

• Last tested on Ubuntu 16.04 LTS (xenial)

This is to set permission for an existing folder for collaboration. This assumes the group name to be dev, and the folder to be /srv/www/project.

This sets setgid bit on the folder.

$ sudo find /srv/www/project -type d -exec chgrp dev {} +
$ sudo find /srv/www/project -type d -exec chmod g+s {} +

Make it writable by the group.

$ sudo chmod -R g+w /srv/www/project

Change group ownership of existing files.

$ sudo chown -R mhan:dev /srv/www/project

These commands should be executed for a new folder.

$ sudo chgrp dev /srv/www/project
$ sudo chmod g+s /srv/www/project

Unpacking gz files

The files are compressed using Lempel-Ziv (LZ77) algorithm. GNU zip (gzip/gunzip) is used for this.

$ gunzip file.gz

or

$ gzip -d file.gz

Zip a folder

$ zip -r test.zip ./test

Mirror a folder

• Last tested on CentOS 8 (2020-06-08)

Copy ALL and keep EVERYTHING same without deleting the source, but deleting files on the target folder that are not found in the source.

$ rsync --delete -HAXavr /source/folder/foldername/ /target/folder/foldername/

• Last tested on Ubuntu 16.04 LTS (xenial)

This also works between servers. The first one is on the same server.

Explanation of parameters used:

• -a: archive - preserve permissions, ownership, and timestamps
• -v: verbose
• -z: compress

$ rsync -azv /folder_a/ /folder_b/

This one is between different servers.

$ rsync -azv ~/folder_a/ mhan@tom.myserver.com:~/folder_b/

Move files older or less than x days

• Last tested on Ubuntu 14.04.5 LTS (trusty)

Make a list of files to copy. Example here is a list of files older than 365 days.

$ find . -type f -mtime +365 > /tmp/rsyncfiles

This is a list of files younger than 365 days

$ find . -type f -mtime -365 > /tmp/rsyncfiles

rsync across the network to another server. This command deletes the source files after they are moved.

$ rsync --remove-source-files -zvh --files-from=/tmp/rsyncfiles . mhan@zinc.wherever.com:/target/folder/