I am a packrat, but I do like a bit of order. This makes maintaining my bash history difficult. There are some commands that I use frequently that seem to fill up my history file making it hard to keep some of the lesser used, yet very important commands in the history. Finally sick of the problem, I poured over the manpage for bash and found the section on HISTCONTROL. From the description there, I found that this along with HISTIGNORE, I can almost eliminate my problem of my bash history getting too full of stupid common commands.
I added this to my ~/.bash_profile:
export HISTIGNORE="&:ls:[bf]g:disown:cd:cd[ ]-:exit:^[ \t]*"
export HISTCONTROL=ignoredups:ignorespace:erasedups
export HISTFILESIZE=2000
Here is the snippet from the bash manual that corresponds to these controls:
HISTCONTROL A colon-separated list of values controlling how commands are saved on the history list. If the list of values includes ignorespace, lines which begin with a space character are not saved in the history list. A value of ignoredups causes lines matching the previous history entry to not be saved. A value of ignoreboth is shorthand for ignorespace and ignoredups. A value of erasedups causes all previous lines matching the current line to be removed from the history list before that line is saved. Any value not in the above list is ignored. If HISTCONTROL is unset, or does not include a valid value, all lines read by the shell parser are saved on the history list, subject to the value of HISTIGNORE. The second and sub- sequent lines of a multi-line compound command are not tested, and are added to the history regardless of the value of HISTCONTROL. HISTFILESIZE The maximum number of lines contained in the history file. When this variable is assigned a value, the history file is truncated, if necessary, by removing the old- est entries, to contain no more than that number of lines. The default value is 500. The history file is also truncated to this size after writing it when an interactive shell exits. HISTIGNORE A colon-separated list of patterns used to decide which command lines should be saved on the history list. Each pattern is anchored at the beginning of the line and must match the complete line (no implicit `*' is appended). Each pattern is tested against the line after the checks specified by HISTCONTROL are applied. In addition to the normal shell pattern matching characters, `&' matches the previous history line. `&' may be escaped using a backslash; the backslash is removed before attempting a match. The second and subsequent lines of a multi-line com- pound command are not tested, and are added to the history regardless of the value of HISTIGNORE.
Cool stuff!
Manpage
Applications supply manpages
Most applications should have manpages with them... I am currently using Ubuntu 10.10. `dpkg -L bash | grep man` shows this:
/usr/share/man
/usr/share/man/man1
/usr/share/man/man1/clear_console.1.gz
/usr/share/man/man1/rbash.1.gz
/usr/share/man/man1/bash.1.gz
/usr/share/man/man1/bashbug.1.gz
/usr/share/man/man7
/usr/share/man/man7/bash-builtins.7.gz
/usr/share/man/man1/sh.1.gz
diverted by dash to: /usr/share/man/man1/sh.distrib.1.gz
The `man` command itself is in the man-db package (run `dpkg -S $(which man)`).
Some other manpages (for libraries and stuff) are in the manpages-dev package.
When all else fails, I do a Google search for 'man whatever'.