HereDoc (Here Document) Usage

Bash Shell

#!/bin/bash

abc=123

# 变量被替换
tclsh <<__CODE__
set abc 456
puts $abc
exit
__CODE__

# 没有变量替换
tclsh <<'__CODE__'
set abc 456
puts $abc
exit
__CODE__

# 结尾处**没有**单引号

echo 789

# Here String

tr a-z A-Z <<< "hello world"

C Shell

#!/bin/csh -f

set abc = 123

# 变量被替换
tclsh <<__CODE__
set abc 456
puts $abc
exit
__CODE__

# 没有变量替换
tclsh <<'__CODE__'
set abc 456
puts $abc
exit
'__CODE__'

# 结尾处**有**单引号

echo 789

# Here String Simulate in C Shell

echo "hello world" | tr a-z A-Z