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Lang/C-Shell/00-LANG.txt

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+{{language
+|exec=interpreted
+|tags=csh
+|hopl id=1936
+}}{{implementation|UNIX Shell}}
+'''csh''' was the shell that William Joy wrote for [[BSD]]. '''csh''' accepted the same [[Unix]] commands as other shells, but had a very different syntax (for variable assignments, control flow, and such). '''csh''' is not compatible with the [[Bourne Shell]].
+
+BSD keeps the C Shell at <code>/bin/csh</code>. [[Hashbang]] lines should use the -f option:
+
+<lang csh>#!/bin/csh -f</lang>
+
+== Reputation ==
+C Shell is obsolete. Most scriptwriters prefer a Bourne-compatible shell, and few users want to learn two flavors of shells. C Shell introduced tilde expansion (<code>ls ~</code>), job control, command history, and aliases, but POSIX shells now have all of those.
+
+[http://www.faqs.org/faqs/unix-faq/shell/csh-whynot/ Csh Programming Considered Harmful] and [http://www.grymoire.com/Unix/CshTop10.txt Top Ten Reasons not to use the C shell] give multiple reasons to avoid C Shell.
+
+tcsh is a later version that fixed many of the problems with csh. It is still actively, if intermittently, maintained and has a following such as on Solaris. 
+
+== Syntax ==
+[http://www.openbsd.org/cgi-bin/man.cgi?query=csh&apropos=0&sektion=1&manpath=OpenBSD+Current&arch=i386&format=html The manual for csh(1)] claims that C Shell has "a C-like syntax". Several other languages have a C-like syntax, including [[Java]] and [[Pike]], and Unix utilities [[AWK]] and [[bc]]. C Shell is less like [[C]] than those other languages.
+
+This example prints a [[Hailstone sequence]] from 13.
+
+{| class="wikitable"
+! C
+! C Shell
+|-
+|| <lang c>#include <stdio.h>
+
+int
+main()
+{
+  int n;
+
+  n = 13;
+  printf("%d\n", n);
+  while (n != 1) {
+    if (n % 2)
+      n = 3 * n + 1;
+    else
+      n /= 2;
+
+    printf("%d\n", n);
+  }
+
+  return 0;
+}</lang>
+|| <lang csh>
+
+
+
+
+
+
+@ n = 13
+echo $n
+while ($n != 1)
+  if ($n % 2) then
+    @ n = 3 * $n + 1
+  else
+    @ n /= 2
+  endif
+  echo $n
+end
+
+
+</lang>
+|}
+
+C Shell has no braces {} to group the commands. Strange keywords are <code>then</code>, <code>endif</code> and <code>end</code>. Expressions have <code>$n</code> instead of <code>n</code>. Assignments use <code>@ n</code>.
+
+C Shell has "a C-like syntax" because C Shell is more like C than [[Bourne Shell]].
+
+{| class="wikitable"
+! Bourne Shell
+! C Shell
+|-
+|| <lang bash>n=13
+echo $n
+while test $n -ne 1; do
+  if expr $n % 2 >/dev/null; then
+    n=`expr 3 \* $n + 1`
+  else
+    n=`expr $n / 2`
+  fi
+  echo $n
+done</lang>
+|| <lang csh>@ n = 13
+echo $n
+while ($n != 1)
+  if ($n % 2) then
+    @ n = 3 * $n + 1
+  else
+    @ n /= 2
+  endif
+  echo $n
+end</lang>
+|}
+
+Bourne Shell requires <code>test</code> or <code>expr</code> to evaluate expressions. C Shell has built-in expressions, so the Hailstone sequence comes more easily. These expressions have a stupid quirk: all operators are right-associative, so <code>10 - 3 - 2</code> acts like <code>10 - (3 - 2)</code>. The fix is to use parentheses.
+
+<lang csh>% @ n = 10 - 3 - 2
+% echo $n
+9
+% @ n = (10 - 3) - 2
+% echo $n
+5</lang>
+
+== Links ==
+* [[OpenBSD]] has [http://www.openbsd.org/cgi-bin/man.cgi?query=csh&apropos=0&sektion=1&manpath=OpenBSD+Current&arch=i386&format=html csh(1) manual] and [http://www.openbsd.org/cgi-bin/cvsweb/src/bin/csh/ source code].

Lang/C-Shell/00-META.yaml

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+---
+from: http://rosettacode.org/wiki/Category:C_Shell

Lang/C-Shell/A+B

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+../../Task/A+B/C-Shell

Lang/C-Shell/Comments

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+../../Task/Comments/C-Shell

Lang/C-Shell/Conditional-structures

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+../../Task/Conditional-structures/C-Shell

Lang/C-Shell/Enforced-immutability

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+../../Task/Enforced-immutability/C-Shell

Lang/C-Shell/Ethiopian-multiplication

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+../../Task/Ethiopian-multiplication/C-Shell

Lang/C-Shell/Execute-a-system-command

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+../../Task/Execute-a-system-command/C-Shell

Lang/C-Shell/Factorial

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+../../Task/Factorial/C-Shell

Lang/C-Shell/FizzBuzz

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+../../Task/FizzBuzz/C-Shell

Lang/C-Shell/Greatest-common-divisor

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+../../Task/Greatest-common-divisor/C-Shell

Lang/C-Shell/Guess-the-number

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+../../Task/Guess-the-number/C-Shell

Lang/C-Shell/Hailstone-sequence

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+../../Task/Hailstone-sequence/C-Shell

Lang/C-Shell/Hello-world-Newline-omission

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+../../Task/Hello-world-Newline-omission/C-Shell

Lang/C-Shell/Hello-world-Standard-error

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+../../Task/Hello-world-Standard-error/C-Shell

Lang/C-Shell/Hello-world-Text

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+../../Task/Hello-world-Text/C-Shell

Lang/C-Shell/Here-document

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+../../Task/Here-document/C-Shell

Lang/C-Shell/Include-a-file

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+../../Task/Include-a-file/C-Shell

Lang/C-Shell/Increment-a-numerical-string

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+../../Task/Increment-a-numerical-string/C-Shell

Lang/C-Shell/Interactive-programming-repl-

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+../../Task/Interactive-programming-repl-/C-Shell

Lang/C-Shell/Least-common-multiple

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+../../Task/Least-common-multiple/C-Shell

Lang/C-Shell/Loop-over-multiple-arrays-simultaneously

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+../../Task/Loop-over-multiple-arrays-simultaneously/C-Shell

Lang/C-Shell/Loops-For

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+../../Task/Loops-For/C-Shell

Lang/C-Shell/Loops-For-with-a-specified-step

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+../../Task/Loops-For-with-a-specified-step/C-Shell

Lang/C-Shell/Loops-Foreach

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+../../Task/Loops-Foreach/C-Shell

Lang/C-Shell/Loops-Infinite

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+../../Task/Loops-Infinite/C-Shell

Lang/C-Shell/Shell-one-liner

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+../../Task/Shell-one-liner/C-Shell

Lang/C-Shell/Short-circuit-evaluation

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+../../Task/Short-circuit-evaluation/C-Shell

Lang/C-Shell/Sieve-of-Eratosthenes

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+../../Task/Sieve-of-Eratosthenes/C-Shell

Lang/C-Shell/Spinning-rod-animation-Text

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+../../Task/Spinning-rod-animation-Text/C-Shell

Lang/C-Shell/String-interpolation-included-

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+../../Task/String-interpolation-included-/C-Shell

Lang/C-Shell/Terminal-control-Dimensions

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+../../Task/Terminal-control-Dimensions/C-Shell

Lang/C-Shell/Terminal-control-Inverse-video

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+../../Task/Terminal-control-Inverse-video/C-Shell