Configuration Information [Automatically generated, do not change]: Machine: x86_64 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='x86_64' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='x86_64-pc-linux-gnu' -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I../. -I.././include -I.././lib -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector-strong -Wformat -Werror=format-security -Wall -no-pie uname output: Linux ubuntu 4.8.10 #1 SMP PREEMPT Mon Nov 21 22:50:58 CST 2016 x86_64 x86_64 x86_64 GNU/Linux Machine Type: x86_64-pc-linux-gnu
Bash Version: 4.4 Patch Level: 5 Release Status: release Description: The manpage said that brace expansion is performed before any other expansions. But I found it's not if it's in a parameter expansion. Repeat-By: $ unset a $ echo ${a:{1..2}} } $ echo ${a:{1..2} $ a=1234 $ echo ${a:{1..2}} bash: a: {1..2: syntax error: operand expected (error token is "{1..2") $ echo ${a:{1..2} bash: a: {1..2: syntax error: operand expected (error token is "{1..2") $ echo ${a:={1..2}} 1234}