Written in C Type Unix shell | Operating system License BSD License | |
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Developer(s) Ken Greer, Paul Placeway, Christos Zoulas, et al. Stable release 6.20.00 / November 24, 2016; 3 months ago (2016-11-24) | ||
tcsh (/ˌtiːˈsiːʃɛl/ "tee-see-shell", /ˈtiːʃɛl/ "tee-shell", or as "tee see ess aitch") is a Unix shell based on and compatible with the C shell (csh). It is essentially the C shell with programmable command-line completion, command-line editing, and a few other features. Unlike the other common shells, functions cannot be defined in a tcsh script and the user must use aliases instead (as in csh). It is the native root shell for BSD-based systems such as FreeBSD.
Contents
History
The “t” in tcsh comes from the “T” in TENEX, an operating system which inspired Ken Greer at Carnegie Mellon University, the author of tcsh, with its command-completion feature. Greer began working on his code to implement Tenex-style file name completion in September 1975, finally merging it into the C shell in December 1981. Mike Ellis at Fairchild A.I. Labs added command completion in September 1983. On October 3, 1983, Greer posted source to the net.sources newsgroup.
Significant features
history command displays the previously-entered commands!! executes the previous command!n executes the nth command that was previously executed!-n executes the command that was executed n commands ago!string executes the most recently executed command that starts with string!?string executes the most recently executed command that contains string!* - refers to all of the arguments from the previous command!$ - refers to the last argument from the previous command!^ - refers to the first argument from the previous command!:n - refers to the nth argument from the previous command!:m-n - refers to the mth through nth arguments from the previous command!:n-$ - refers to the nth through the last argument from the previous command!# - argument selector for all arguments, including the alias/command itself; arguments need not be supplied.!* - argument selector for all arguments, excluding the alias/command; arguments need not be supplied.!$ - argument selector for the last argument; argument need not be supplied, but if none is supplied, the alias name is considered to be the last argument.!^ - argument selector for first argument; argument MUST be supplied.!:n - argument selector for the nth argument; argument MUST be supplied; n=0 refers to the alias/command name.!:m-n - argument selector for the arguments from the mth to the nth; arguments MUST be supplied.!:n-$ - argument selector for the arguments from the nth to the last; at least argument n MUST be supplied.
where command. Works like the which command but shows all locations of the target command in the directories specified in $PATH rather than only the one that will be used.Deployment
Early versions of Mac OS X shipped with tcsh as the default shell, but the default for new accounts is bash as of 10.3. (tcsh is still provided, and upgrading the OS does not change the shell of any existing accounts). The tcsh is the default root shell of FreeBSD (the default user shell is POSIX-based) and its descendants like DragonFly BSD and DesktopBSD.