Echo (command)

The command is available the following shells or at least one shell of a listed operating system: • Unix and Unix-like shells • Windows • Multics • OS/2 • DOS • TSC FLEX • MetaComCo TRIPOS • Zilog Z80-RIO • OS-9 • Panos • FlexOS • ReactOS • MPE/iX • KolibriOS • SymbOS • EFI shell. ==History==

echo began within Multics. After it was programmed in C by Doug McIlroy as a "finger exercise" and proved to be useful, it became part of Version 2 Unix. echo -n in Version 7 replaced prompt, (which behaved like echo but without terminating its output with a line delimiter). On PWB/UNIX and later Unix System III, echo started expanding C escape sequences such as \n with the notable difference that octal escape sequences were expressed as \0ooo instead of \ooo in C. Eighth Edition Unix echo only did the escape expansion when passed a -e option, and that behaviour was copied by a few other implementations such as the builtin echo command of Bash or zsh and GNU echo. On MS-DOS, the command is available in versions 2 and later. ==Examples==

C:\>echo Hello world Hello world Using ANSI escape code SGR sequences, compatible terminals can print out colored text. Using a UNIX System III-style implementation: BGRED=`echo "\033[41m"` FGBLUE=`echo "\033[35m"` BGGREEN=`echo "\033[42m"` NORMAL=`echo "\033[m"` Or a Unix Version 8-style implementation (such as Bash when not in Unix-conformance mode): BGRED=`echo -e "\033[41m"` FGBLUE=`echo -e "\033[35m"` BGGREEN=`echo -e "\033[42m"` NORMAL=`echo -e "\033[m"` and after: echo "${FGBLUE} Text in blue ${NORMAL}" echo "Text normal" echo "${BGRED} Background in red" echo "${BGGREEN} Background in Green and back to Normal ${NORMAL}" Portably with printf: BGRED=`printf '\33[41m'` NORMAL=`printf '\33[m'` printf '%s\n' "${BGRED}Text on red background${NORMAL}" ==See also==