Overview The history command displays a list of previously executed commands in the current Nash shell session. Each command is shown with a line number for easy reference.
Syntax Description The history command shows commands that have been executed in the current interactive Nash session. Commands are numbered sequentially starting from 1. An optional argument can limit the output to the last N entries.
Arguments Limit output to the last N history entries. If not specified, all history entries are displayed.
Examples Display All History history # Output: # 1 ls # 2 cd /home/user # 3 cat file.txt # 4 grep pattern data.txt # 5 history
Display Last N Commands history 3 # Output: # 3 cat file.txt # 4 grep pattern data.txt # 5 history 3
Display Last 10 Commands history 10 # Shows the last 10 commands executed
Display Single Last Command history 1 # Output: # 5 history 1 # (shows only the most recent command)
Each line follows this format:
Line numbers are right-aligned and padded with spaces
Line numbers are at least 5 characters wide
Two spaces separate the line number from the command
Commands are shown exactly as they were entered
Practical Use Cases Review Recent Commands history 20 # Review the last 20 commands to recall what you've done
Find Previously Used Commands history | grep git # Find all git commands in history
Search for Specific Pattern history | grep -i api # Find all commands containing "api" (case-insensitive)
Count Total Commands history | wc -l # Output: 42 # Shows total number of commands in history
Extract Command by Number history | grep "^ 5" # Find command number 5
Recent Command Summary echo "Last 5 commands:" history 5
Audit Session Activity # Save history to file for review history > session-log.txt echo "Session saved to session-log.txt"
Filter by Command Type # Find all file operations history | grep -E "cp|mv|rm|touch" # Find all text processing history | grep -E "grep|sed|awk|cut" # Find all directory operations history | grep -E "cd|mkdir|ls|pwd"
Check Command Frequency # Find most commonly used commands history | cut -c8- | cut -d ' ' -f1 | sort | uniq -c | sort -rn
Review Long Commands # Find commands longer than 50 characters history | grep -E ".{50,}"
Combining with Other Commands Filter and display
Count specific commands
Last command only
Extract command text
history | grep export # Output: # 7 export API_KEY=abc123 # 12 export PORT=8080
History Persistence Nash command history is session-based and not persistent :
History is stored in memory only
History is cleared when the shell exits
Each new Nash session starts with empty history
No history file is saved to disk by default
If you need to preserve history between sessions, manually save it: history > ~/.nash_history
Interactive Session Only The history command only works in interactive mode: # Interactive shell (works) nash user@nash$ history # Shows history # Non-interactive (empty) nash -c "history" # Shows nothing (no interactive history) # Script file (empty) echo "history" > script.sh nash script.sh # Shows nothing (no interactive history)
History Size Nash maintains unlimited history during a session (memory permitting). There is no built-in limit on the number of commands stored.
# Check history size history | wc -l # Returns total number of commands in current session
Command Recall While Nash stores command history, it currently does not support:
History expansion (!N, !!, !string)
Reverse history search (Ctrl+R)
History substitution
History is view-only via the history command. Limiting Output Examples # Last 5 commands history 5 # Last 10 commands history 10 # Last 100 commands history 100 # All commands (no limit) history
Notes
History starts at line number 1
Each executed command is immediately added to history
The history command itself appears in history
Line numbers are sequential and don’t skip
Empty commands are not added to history
Invalid limit values are ignored (shows all history)
Common Patterns Session Documentation # At end of session, save history with timestamp echo "Session $( date )" > session-notes.txt history >> session-notes.txt
Recent Activity Check echo "Recent activity:" history 10
Command Statistics echo "Total commands: $( history | wc -l )" echo "Last command: $( history 1 | cut -c8- )"
Find Command with Pattern # Find all export commands history | grep "^.*export"
Exit Status The history command always returns exit code 0 (success).
help - Display help informationwhich - Check command availabilitygrep - Filter history outputcat - View saved history files 