Bash

Bash Conditionals

Check 6.4 Bash Conditional Expressions or the manpage man test for more information.

Option	Explanation
-a file	True if file exists.
-b file	True if file exists and is a block special file.
-c file	True if file exists and is a character special file.
-d file	True if file exists and is a directory.
-e file	True if file exists.
-f file	True if file exists and is a regular file.
-g file	True if file exists and its set-group-id bit is set.
-h file	True if file exists and is a symbolic link.
-k file	True if file exists and its "sticky" bit is set.
-p file	True if file exists and is a named pipe (FIFO).
-r file	True if file exists and is readable.
-s file	True if file exists and has a size greater than zero.
-t fd	True if file descriptor fd is open and refers to a terminal.
-u file	True if file exists and its set-user-id bit is set.
-w file	True if file exists and is writable.
-x file	True if file exists and is executable.
-G file	True if file exists and is owned by the effective group id.
-L file	True if file exists and is a symbolic link.
-N file	True if file exists and has been modified since it was last read.
-O file	True if file exists and is owned by the effective user id.
-S file	True if file exists and is a socket.
file1 -ef file2	True if file1 and file2 refer to the same device and inode numbers.
file1 -nt file2	True if file1 is newer (according to modification date) than file2, or if file1 exists and file2 does not.
file1 -ot file2	True if file1 is older than file2, or if file2 exists and file1 does not.
-o optname	True if the shell option optname is enabled. The list of options appears in the description of the -o option to the set builtin (see The Set Builtin).
-v varname	True if the shell variable varname is set (has been assigned a value).
-R varname	True if the shell variable varname is set and is a name reference.
-z string	True if the length of string is zero.
-n string	True if the length of string is non-zero.
string1 == string2, string1 = string2	True if the strings are equal. When used with the [[ command, this performs pattern matching as described above (see Conditional Constructs). ‘=’ should be used with the test command for POSIX conformance.
string1 != string2	True if the strings are not equal.
string1 < string2	True if string1 sorts before string2 lexicographically.
string1 > string2	True if string1 sorts after string2 lexicographically.
arg1 OP arg2	OP is one of ‘-eq’, ‘-ne’, ‘-lt’, ‘-le’, ‘-gt’, or ‘-ge’. These arithmetic binary operators return true if arg1 is equal to, not equal to, less than, less than or equal to, greater than, or greater than or equal to arg2, respectively. Arg1 and arg2 may be positive or negative integers. When used with the [[ command, Arg1 and Arg2 are evaluated as arithmetic expressions (see Shell Arithmetic).

Bash Prompt Escape Sequences

Check tldp.org.

Escape Sequence	Description
\a	an ASCII bell character (07)
\d	the date in "Weekday Month Date" format (e.g., "Tue May 26")
\e	an ASCII escape character (033)
\h	the hostname up to the first .
\H	the hostname
\j	the number of jobs currently managed by the shell
\l	the basename of the shell's terminal device name
\n	newline
\r	carriage return
\s	the name of the shell, the basename of $0 (the portion following the final slash)
\t	the current time in 24-hour HH:MM:SS format
\T	the current time in 12-hour HH:MM:SS format
\@	the current time in 12-hour am/pm format
\u	the username of the current user
\v	the version of bash (e.g., 2.00)
\V	the release of bash, version + patchlevel(e.g., 2.00.0)
\w	the current working directory
\W	the basename of the current working directory
\!	the history number of this command
\#	the command number of this command
\$	if the effective UID is 0, a #, otherwise a $
\nnn	the character corresponding to the octal number nnn
\\	a backslash
\[	begin a sequence of non-printing characters, which could be used to embed a terminal control sequence into the prompt
\]	end a sequence of non-printing characters

Bash Profile

Basic $HOME/.profile

if [ -f "$HOME/.bashrc" ]; then
        source "$HOME/.bashrc"
fi

Basic $HOME/.bashrc

PS1='\[\033[01;32m\]\u@\h\[\033[00m\]:\[\033[01;34m\]\w\[\033[00m\]\$ '

alias ls='ls -p --color'
alias la='ls -al'
alias ll='ls -l'

Bash Quoting

See quoting manual