tcsh

tcsh is a shell imperative and scripting language first appearing in 1983.

Hello World

#!/usr/bin/env tcsh

echo "Hello World!"

Coding Guide

Language Version

tcsh (TENEX C Shell) - Enhanced C shell with command-line editing and completion

Execution Model

• Interpreted shell script
• Code executes directly from source
• Scripts run line-by-line from top to bottom

Key Characteristics

• C shell variant with enhancements
• Case-sensitive
• Variables: set VAR=value (use set keyword)
• Command substitution: `command` or $(command)
• String interpolation: "$VAR" or "${VAR}"
• Arrays: set ARRAY=(item1 item2 item3)
• Arithmetic: @ VAR = expression (use @ for arithmetic)
• Pattern matching: =~ operator in conditionals
• C-like syntax for conditionals: if (condition) then ... endif

Fragment Authoring

Write valid tcsh shell commands. Your fragment becomes the script body. The fragment code will execute as part of the shell script.

Available Commands

Standard Unix utilities and tcsh built-ins are available:

• echo - Print text
• printf - Formatted output
• test - Conditional tests
• if, while, foreach, switch - Control structures
• grep, sed, awk - Text processing
• Standard Unix utilities

Common Patterns

• Output: echo "message" or printf "%s\n" "message"
• Variables: set NAME="value" and echo "$NAME"
• Arrays: set ARRAY=(1 2 3) and echo "$ARRAY[1]"
• Conditionals: if (condition) then ... endif
• Loops: foreach i (1 2 3 4 5); echo "$i"; end
• Command substitution: set RESULT=\command``
• Arithmetic: @ VAR = expression (use @ for arithmetic operations)
• Functions: alias function_name 'commands'

Examples

# Simple output
echo "Hello from fragment!"

# Variables
set NAME="Alice"
echo "Hello, $NAME!"

# Arithmetic
@ A = 5
@ B = 10
@ SUM = $A + $B
echo "Sum: $SUM"

# Arrays
set FRUITS=(apple banana cherry)
foreach fruit ($FRUITS)
    echo "Fruit: $fruit"
end

# Conditionals
if ("test" == "test") then
    echo "Testing mode"
else
    echo "Normal mode"
endif

# While loops
@ i = 1
while ($i <= 5)
    echo "Count: $i"
    @ i++
end

# Command substitution
set DATE=`date`
echo "Current date: $DATE"

# Array indexing
set ARRAY=(one two three)
echo "First: $ARRAY[1]"
echo "All: $ARRAY"

# String operations
set STR="Hello World"
echo "Length: $#STR"
echo "First word: $STR[1]"

Caveats

• Variable assignment: use set VAR=value (not VAR=value like bash)
• Arithmetic: use @ VAR = expression (not $((expression)))
• Conditionals: use if (condition) then ... endif (C-like syntax)
• Arrays: use set ARRAY=(items) and access with $ARRAY[index] (1-indexed)
• Loops: use foreach or while with end (not done like bash)
• Command substitution: use backticks `command` or $(command)
• String length: use $#VAR (not ${#VAR})
• Case-sensitive variable names
• Use @ for arithmetic operations, not $((...))
• Array indexing starts at 1, not 0

Fraglet Scripts

Echo Args

#!/usr/bin/env -S fragletc --vein=tcsh
echo "Args: $argv"

Stdin Upper

#!/usr/bin/env -S fragletc --vein=tcsh
set line = $<
echo "$line" | tr "a-z" "A-Z"

Tcsh Fortune

#!/usr/bin/env -S fragletc --vein=tcsh
# One from the vault: tcsh fortunes
echo "tcsh: the C shell that outlived the punch card."

Test

#!/usr/bin/env -S fragletc --vein=tcsh

echo "Hello World!"

Container Info