bash.md

Bash

How to set command line input mode?

Vi mode:

set -o vi

Emacs mode (default):

set -o emacs

How to show last command?

To show the command in command-line press <Ctrl+P>.

Use built-in command fc to open some editor and insert last command into it.

How to check whether path is a directory?

if [ -d "$path" ]; then
    # $path is a path a directory that exists
fi

Other useful operators:

-d - File exists and it is a folder
-e - File exists
-r - You have a right to read a file
-s - File exists and it's not empty
-w - You have a right wo write to a file
...

How to find all files with names that match a given pattern?

In a current directory:

find . -name "<pattern>"

How to rename all files with names that match a given pattern?

find . -name "<pattern>" | while read fname; do mv $fname ${fname/<from>/<to>}; done

You can use echo for debugging:

find . -name "<pattern>" | while read fname; do echo "mv $fname ${fname/<from>/<to>}"; done

For more verbosity do this:

find . -name "<pattern>" | while read fname; do echo "mv $fname ${fname/<from>/<to>}"; done | bach -x

while read

while read is a very useful stuff. You can redirect output from one app with pipe to while read construction and do anything you want with it on bash:

smth | while read line; do echo $line; done