In reality you have quite often perform a certain command on several files. First i detect all files I’m looking for and store them in a filelist.

Second i run through this file, line by line and perform my command on all filename I’ve received one step before.

You need to replace in several files. You can do it with sed. Be aware about masking special chars. In the example below the string „my\folder“ is replaced with „your\folder“.
Replacing with sed works like this: sed -i s#old#new#g
The delimiter (in this case the #) can be changed. The first sign after the s acts as delimiter.

 

Getting the size of all files and folders inside the current directory can be done by typing:

Get filesize in descending order from all files in a recursive folder structure

Another quite handy tool is ncdu. It provides you the disc usage in a graphical way on the shell. Install it like this:

List folders bigger 1Mb and list them in descending order

List the ten largest folders inside a recursive folder structure

 

Find files and file content on the terminal can be achieved by the use of the find tool.

By far one of the best tools is „Silversearcher ag“, install it with sudo apt-get install silversearcher-ag. If you want to search for example recursive all folders, only php files for the search string „my Value“, simply type:

Find file/s containing a specific string in its name:

Now list all files that contain the word „searchTerm“

List all the occurrence and their respective line-number of „searchTerm“ in files. The parameter -n toggles the line-number, the parameter -H toggles the filename.

A handy tool as well is ack-grep (you have to install it first). Be sure to wrap the search-term in single quotes.