Tag: Shell

The different extended pattern matching operators are listed below, where pattern-list is a list containing one or more filenames, separated using the | character:

1. *(pattern-list) – matches zero or more occurrences of the specified patterns
2. ?(pattern-list) – matches zero or one occurrence of the specified patterns
3. +(pattern-list) – matches one or more occurrences of the specified patterns
4. @(pattern-list) – matches one of the specified patterns
5. !(pattern-list) – matches anything except one of the given patterns

To use them, enable the extglob shell option as follows:

# shopt -s extglob

1. To delete all files in a directory except filename, type the command below:

$ rm -v !("filename")

2. To delete all files with the exception of filename1 and filename2:

$ rm -v !("filename1"|"filename2") 

Source: 3 Ways to Delete All Files in a Directory Except One or Few Files with Extensions

In bash scripting, the replacement of string is important because it allows you to modify a variable and the text of a file. It also helps in file and text processing and to validate user input.

To replace a string in bash, check the following methods:

1. Using Parameter expansion: ${String/pattern/replacement}
2. Using the sed command: sed 's/pattern/replacement/' filename
3. Using the awk command: "input_str" | awk 'pattern { action }'
4. Using the perl command: perl [options] -e 'action' filename
5. Using the tr command: tr 'old_chars' 'new_chars' < "input_file"

Dive into the article to learn these methods of how to replace a bash string in detail.

Source: How to Replace String in Bash? [5 Methods] – LinuxSimply