gam@proper.UUCP (Gordon Moffett) (06/24/84)
It was begining to frustrate me that the csh ``alias'' command accepted only one-line definitions; it is impossible to have an alias that uses ``if-then-else''. My solution to this problem was using a combination of ``source'' and ``alias'' allow possibly lengthy alias-type commands using more complex csh constructions. This is particularly applicable in the following examples. The UniSoft port I am using does not support the ``pushd'' and ``popd'' commands of csh, so I have implimented them thus: [in my .cshrc]: alias popd 'set argv = (\!*) ; source ~/csh/popd' alias pushd 'set argv = (\!*) ; source ~/csh/pushd' [~/csh/popd]: if (! $?_dirstack || $#_dirstack < 1) then echo "popd: Directory stack empty." else chdir $_dirstack[1] echo $_dirstack shift _dirstack endif [~/csh/pushd]: if ($#argv != 1) then echo "pushd: Arg count." else if (! $?_dirstack) set $_dirstack = () set _dirstack = (`pwd` $_dirstack) chdir $argv echo $argv $_dirstack endif The advantages to this method are: o More sophisticated (multi-line) csh constructs are allowed o Operates on the current shell (qv, chdir) o No overhead for reading .cshrc (as with an executable script) The disadvantages are: o Argv probably should be saved somewhere and restored o No ``exit'' from ``if'' statements (other than -- ech -- ``goto'') o Requires a file access [ These scripts were derived from someone else's implimentation of pushd/popd for csh's lacking them; I don't recall who that is, but thank you anyway ] [ Also do not use this as launch-point for another csh vs sh argument as it is not my intention to start one -- I shouldn't have to say this but I've been on the net for a while ... ] Comments and discussion are encouraged. -- Gordon A. Moffett { hplabs!nsc, decvax!sun!amd, ihnp4!dual } !proper!gam
mats@dual.UUCP (Mats Wichmann) (06/26/84)
RE: Gordon's neato implementation of pushd/popd for csh's that don't have them.... >> [in my .cshrc]: >> alias popd 'set argv = (\!*) ; source ~/csh/popd' >> alias pushd 'set argv = (\!*) ; source ~/csh/pushd' >> [~/csh/popd]: >> if (! $?_dirstack || $#_dirstack < 1) then >> echo "popd: Directory stack empty." >> else >> chdir $_dirstack[1] >> echo $_dirstack >> shift _dirstack >> endif >> [~/csh/pushd]: >> if ($#argv != 1) then >> echo "pushd: Arg count." >> else >> if (! $?_dirstack) set $_dirstack = () >> set _dirstack = (`pwd` $_dirstack) >> chdir $argv >> echo $argv $_dirstack >> endif I am not trying to criticise the intent of the article, which was to show a method for fudging more complex alias commands. However, the specific example used can be done more quickly, although it is not as complete an emulation... Try this (all in your .cshrc) if (! $?_d ) set _d = () alias pushd set _d = \(\`pwd\` \$_d\) \; cd \!\* alias popd cd \$_d\[1\] \; echo \$_d\[1\] : \; shift _d Avoids opening an extra file each time for the source, although it has a less elegant error recovery...I use it quite a bit when jumping around the system. Mats
janney@unm-cvax.UUCP (06/30/84)
Re: using an alias to source a longer file This can also be used to get which(1) to provide more up-to-date information about your aliases: alias which 'set argv=(\!*); source /usr/ucb/which; unset noglob' Of course, it does zap argv, which might be a problem sometimes. Jim Janney {{convex,ucbvax,gatech}!unmvax, {purdue,lbl-csam,cmcl2}!lanl-a}!unm-cvax!janney
lamarche@micomvax.UUCP (07/18/84)
Header