Bash
Verificar quais shell são disponíveis no sistema
[user]$ more /etc/shells /bin/sh /bin/bash /sbin/nologin /bin/zsh
/bin/bash
The program /bin/bash uses a set of startup files in /etc or an equivalent file in your home directory.
- Interactive login shell: /bin/login
- after reading /etc/passwd file
- reads /etc/profile
- reads ~/.bash_profile
- Interactive non-login shell: at the command-line using a shell program (e.g., [prompt]$/bin/bash) or by the /bin/su command. An interactive non-login shell is also started with a terminal program such as xterm or konsole from within a graphical environment.
- Normally copies the parent environment
- reads ~/.bashrc
- Non-interactive shell: usually present when a shell script is running. Only the environment inherited from the parent shell is used.
- ~/.bash_logout: read and executed when a user exits from an interactive login shell.
- /etc/bashrc : for system wide initialization of non-login shells. This file is usually called from the user's ~/.bashrc file and is not built directly into bash itself. This convention is followed in this section.
/etc/profile
Alguns arquivos importantes:
colorls.sh % ls colorido
lang.sh % definicoes do charset usado, LANG, LC_CTYPE
mpich2.sh % module load mpich2-x86_64
vim.sh % para o vi
shell-colors.sh % ADICIONADO. Contém atalhos para cores e o comando para mudar a cor do prompt
% PS1="${BOLDYELLOW}\u${BOLDWHITE}@${BOLDGREEN}\h ${BOLDBLUE}\W \$ ${COLOR_RESET}"
Expressões Condicionais no Bash
6.4 Bash Conditional Expressions
Usados pelo comando [[ e o comando test e [ .
When used with ‘[[’, The ‘<’ and ‘>’ operators sort lexicographically using the current locale.
Unless otherwise specified, primaries that operate on files follow symbolic links and operate on the target of the link, rather than the link itself.
-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.
-O file
True if file exists and is owned by the effective user id.
-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.
-S file
True if file exists and is a socket.
-N file
True if file exists and has been modified since it was last read.
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.
file1 -ef file2
True if file1 and file2 refer to the same device and inode numbers.
-o optname
True if 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).
-z string
True if the length of string is zero.
-n string string
True if the length of string is non-zero.
string1 == string2 string1 = string2
True if the strings are equal. ‘=’ 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.
