Advanced Bash Commands

Welcome to the repository for advanced Bash commands! This guide provides explanations and examples for commonly used Bash commands, along with additional details about specific options and terminologies.

Table of Contents

• File and Directory Operations
• File Permissions
• Text Processing
• Viewing and Filtering
• Scripting and Automation
• Additional Commands
• Contributing

File and Directory Operations

• pwd
  Display the present working directory path.

• ls
  List directories and files in a folder.

• ls -R
  List subdirectories recursively.
  -R: Recursive listing of directories and their contents.

• ls -t
  List files sorted by modification time.
  -t: Sort by modification time, newest first.

• ls -l
  List files with permissions, modification date, and size.
  -l: Long listing format, including file permissions, number of links, owner, group, size, and modification date.

• ls -lt
  List files sorted by modification time with time included.
  -lt: Combines -l (long format) and -t (time sorting).

• ls -la
  List all items including hidden items.
  -a: List all files, including hidden ones (those starting with a dot).

• ls -lRa
  Recursively list all items including hidden ones.
  -R: Recursive listing.
  -a: Include hidden files.

• ls -lr
  List files in reverse order.
  -r: Reverse the order of the sort.

• ls -s
  List directories by size.
  -s: Display file sizes in blocks.

• ls *.FILE_EXTENSION_NAME
  List files with a specific extension.

• ls Zoo*
  List files starting with "Zoo".

• ls ..
  List directories and folders in the parent directory.

• cd
  Change to a specified directory.

• cd ..
  Move up one directory.

• cd ../../
  Move up two directories.

• touch filename
  Create an empty file.

• cat filename
  View the contents of a file.

• cat > filename
  Write to a file. Use Ctrl + D to save and exit, Ctrl + C to exit without saving.

• cat >> filename
  Append to an existing file.

• mkdir dirname
  Create a new directory.

• mkdir test && cd test
  Create a new directory and navigate into it.

• mkdir -p path/to/dir
  Create nested directories.
  -p: Create parent directories as needed.

• mv source destination
  Move or rename files or directories.

• cp source destination
  Copy files or directories.

• cp -r source destination
  Copy directories recursively.
  -r: Recursively copy directories and their contents.

• rm filename
  Remove a file.

• rm -r directory
  Remove a directory and its contents.
  -r: Recursively remove directories and their contents.

File Permissions

• chmod ugo-rwx filename
  Remove all permissions for user, group, and others.
  ugo: User, group, others.

• chmod -R ugo+rwx directory
  Recursively add read, write, and execute permissions to a directory.
  -R: Recursively apply changes.

• chmod u+x filename
  Add execute permission for the user.
  u+x: User execute permission.

• chmod g+wx filename
  Add write and execute permissions for the group.
  g+wx: Group write and execute permissions.

• chmod u-x filename
  Remove execute permission for the user.
  u-x: User execute permission removal.

• chmod 664 filename
  Set file permissions using octal notation: 6 (read and write) for user and group, 4 (read) for others.
  664: Octal representation of file permissions.

• chmod 777 filename
  Set full permissions (read, write, execute) for user, group, and others.
  777: Octal representation of full permissions.

Text Processing

• grep "pattern" filename
  Search for lines containing a pattern.

• grep -c "pattern" filename
  Count the number of lines containing a pattern.
  -c: Count the number of matching lines.

• grep -h "pattern" filename
  Search for a pattern without showing filenames (useful for multiple files).
  -h: Suppress filenames in the output.

• grep -i "pattern" filename
  Search for a pattern case-insensitively.
  -i: Case-insensitive search.

• grep -n "pattern" filename
  Search for a pattern and include line numbers.
  -n: Display line numbers with matching lines.

• grep -w "pattern" filename
  Match whole words only.
  -w: Match the whole word.

• grep -o "pattern" filename
  Print only the matched parts of a line.
  -o: Only show the matched parts.

• grep -v "pattern" filename
  Invert the match: show lines that do not contain the pattern.
  -v: Invert the match.

• grep -A 5 "pattern" filename
  Show 5 lines after the matching pattern.
  -A: Number of lines to show after a match.

• grep -B 5 "pattern" filename
  Show 5 lines before the matching pattern.
  -B: Number of lines to show before a match.

• grep -C 5 "pattern" filename
  Show 5 lines before and after the matching pattern.
  -C: Number of lines to show around a match.

Viewing and Filtering

• head filename
  View the first 10 lines of a file.

• head -n 20 filename
  View the first 20 lines of a file.
  -n: Number of lines to display.

• tail filename
  View the last 10 lines of a file.

• tail -n +25 filename | head -n 5
  View lines 25 through 30 of a file.
  -n +25: Start showing lines from line 25.
  | head -n 5: Pipe the output to head to show the first 5 lines of the result.

• wc filename
  Display line count, word count, and character count of a file.

Scripting and Automation

• sed -n '/pattern/ p' filename
  Print lines matching a pattern (using -n to suppress default output).
  -n: Suppress automatic printing of pattern space.
  p: Print lines that match the pattern.

• sed 's/pattern/replacement/' filename
  Substitute the first occurrence of a pattern with a replacement.
  s/pattern/replacement/: Substitution command.

• sed -i.bak 's/pattern/replacement/' filename
  Edit a file in-place and create a backup with .bak extension.
  -i.bak: Edit files in-place and save the original file as .bak.

• sed '3 s/old/new/' filename
  Replace text on line 3.
  3: Line number where substitution occurs.

• sed '3,5 s/old/new/' filename
  Replace text from lines 3 to 5.
  3,5: Range of lines for substitution.

• sed -n '3,/pattern/ p' filename
  Print lines from line 3 until a pattern is matched.
  -n: Suppress automatic printing.
  3,/pattern/: Start from line 3 until the pattern is matched.

• awk '/pattern/{print $0}' filename
  Print lines matching a pattern.

• awk '{gsub(/pattern/, "replacement")}{print}' filename
  Substitute all occurrences of a pattern with a replacement.
  gsub(/pattern/, "replacement"): Global substitution function in awk.

• awk 'BEGIN {print "Header"} {print} END {print "Footer"}' filename
  Add text at the beginning and end of a file.
  BEGIN: Code block executed before processing any lines.
  END: Code block executed after processing all lines.

• awk -F "," '{print $1, $2}' filename
  Print the first and second columns of a CSV file.
  -F ",": Set field separator to comma.

• awk '{count[$2]++} END {print count["value"]}' filename
  Count occurrences of a value in the second column.
  count[$2]++: Increment count of each value in the second column.

• awk '{ if ($1 > 1598863888 ) {print $0} }' log.txt
  Print lines where the first column is greater than a specific value.

Additional Commands

• find /path -name "*.ext"
  Find files with a specific extension.
  -name "*.ext": Match files with the specified extension.

• sort filename
  Sort lines of a file.

• uniq filename
  Remove duplicate lines from a file.

• diff file1 file2
  Compare two files line by line.

Contributing

Feel free to contribute to this repository by opening issues or submitting pull requests. Your contributions help improve this guide and make it more useful for others.