pfalstad@phoenix.princeton.edu (Paul Falstad) (05/29/91)
Submitted-by: Paul Falstad <pfalstad@phoenix.princeton.edu>
Posting-number: Volume 20, Issue 22
Archive-name: zsh2.00/patch03a
Patch-To: zsh2.00: Volume 18, Issue 84-98
Included in this patchlevel is a 36-page TeX document,
"An Introduction to the Z Shell", which gives a lot of examples
and information on why anyone would want to use zsh. The first
two parts of this patch contain this document, and may be unsharred
separately.
Part of the README follows, and then part 1 of the patch itself.
---
To get this shell running, cd into the src directory and type
"buildzsh". I tested it on the following machines, where it compiled
just by running this script:
Sun SPARCServer 4/490 running SunOS 4.1.1
Sun 3/60C running SunOS 4.1.1
Sun 3/50M running SunOS 4.0
NeXTstation running Mach 2.0
hp9000 running BSD 4.3
DECSystem-5000 running ULTRIX 4.0
02-03:
- two stupid bugs that were introduced in the last patch were fixed:
- multiple command substitution on a line failed
- a file descriptor leak caused the shell to crash after a while
- added 'An Introduction to the Z Shell'
- behaves properly when the tty session dies suddenly
- had a serious memory leak on some systems
- the test and [ builtins have been added, although [[...]]
is more efficient
- in your prompt, %m2 now prints foo.bar, %m3 prints foo.bar.com, etc.
- the -D and -P options to print have been added
- the NULLCMD and ZDOTDIR parameters have been added
- ${*:-foo} works
- "$@" and "$arr[@]" work like ksh
- .zprofile is sourced before .zshrc in login shells
- the CSHJUNKIEQUOTES and PUSHDMINUS options have been added
- REAL_TTY compilation switch added
- aliases beginning with a space cause the history line to be junked
if HISTIGNORESPACE is set
- echo prints bad options instead of complaining about them
- "set -o" no longer dumps core
- "alias a=alias; date >a" no longer creates a file called "alias"
- "function foo() \n { date }" is now legal (the () and the newline
are allowed)
- nested brace expressions work properly
- disabled commands stay disabled after a rehash (or after the shell
finishes sourcing your .zshrc)
- corrected aliases work
- executables in the currect directory are now completed
- in "case foo", "foo" is not interpreted as a directory name with autocd
- aliases were not always interpreted properly after a completion
- bindkey '^?' didn't work
- echo ${HOST:-{bar}} didn't work
- editor update is more efficient in some cases
- menucomplete works even better
- assign to an array element "foo[1]=bar" didn't always work
- doesn't print directories like "~tmp" if HOME=/
- quotes in case statement patterns caused problems
- pressing ^C right after typing "fc" caused the editor to share
the tty with the shell
- echo $(echo 2) produced no output, but echo $(echo x) worked fine (weird)
Paul Falstad pfalstad@phoenix.princeton.edu
---cut here---cut here---cut here---cut here---cut here---cut here---
#!/bin/sh
# patch03a
# This is a shell archive (produced by shar 3.49)
# To extract the files from this archive, save it to a file, remove
# everything above the "!/bin/sh" line above, and type "sh file_name".
#
# Extract this _inside_ the zsh2.00 directory, unlike
# previous patches.
#
# made 05/26/1991 03:48 UTC by pf@dendrite
# Source directory /home/learning/pf/zsh/zsh2.00
#
# existing files will NOT be overwritten unless -c is specified
#
# do not concatenate these parts, unpack them in order with /bin/sh
#
# This shar contains:
# length mode name
# ------ ---------- ------------------------------------------
# 56686 -rw-r--r-- doc/zshintro.tex
#
if test -r _shar_seq_.tmp; then
echo 'Must unpack archives in sequence!'
echo Please unpack part `cat _shar_seq_.tmp` next
exit 1
fi
# ============= doc/zshintro.tex ==============
if test ! -d 'doc'; then
echo 'x - creating directory doc'
mkdir 'doc'
fi
if test -f 'doc/zshintro.tex' -a X"$1" != X"-c"; then
echo 'x - skipping doc/zshintro.tex (File already exists)'
rm -f _shar_wnt_.tmp
else
> _shar_wnt_.tmp
echo 'x - extracting doc/zshintro.tex (Text)'
sed 's/^X//' << 'SHAR_EOF' > 'doc/zshintro.tex' &&
% this is TeX, not LaTex
\newskip\ttglue
\ttglue=.5em plus .25em minus .15em
\outer\def\begindisplay{\obeylines\startdisplay}
{\obeylines\gdef\startdisplay#1
X {\catcode`\^^M=5$$#1\halign\bgroup\indent##\hfil&&\qquad##\hfil\cr}}
\outer\def\enddisplay{\crcr\egroup$$}
\def\ttverbatim{\begingroup \catcode`\\=12 \catcode`\{=12
\catcode`\}=12 \catcode`\$=12 \catcode`\&=12
\catcode`\#=12 \catcode`\%=12 \catcode`\~=12
\catcode`\_=12 \catcode`\^=12
\obeyspaces \obeylines \tt}
{\obeyspaces\gdef {\ }}
X
\outer\def\beg{\parindent=20pt $$\let\par=\endgraf \ttverbatim \parskip=0pt
\catcode`\@=0 \rightskip=-5pc \ttfinish}
{\catcode`\@=0 @catcode`@\=12
@obeylines
@gdef@ttfinish#1^^M#2\end{#1@vbox{#2}@endgroup$$@parindent=0pt}}
X
\catcode`\@=13
\def\@{\char`\@}
\def\opt#1{{\sl #1}}
\def\parm#1{{\bf #1}}
{\obeylines\gdef@{\ttverbatim\spaceskip=\ttglue\let^^M=\ \let@=\endgroup}}
\parskip=9pt \parindent=0pt
\def\C#1#2{\hbox{\sl \char`\^#2}}
\def\c#1{{\sl \char`\^#1}}
\def\E#1#2{\hbox{\sl ESC-#2}}
\def\e#1{{\sl ESC-#1}}
\def\TAB{\hbox{\sl TAB}}
\def\curs#1#2{\underbar{#2}}
\def\ecurs{\underbar{\ }}
\def\dot{$\ldots$}
\def\space{\ }
\nopagenumbers
\headline={\rm\ifnum\pageno<2\hfil\else
X An Introduction to the Z Shell\hfil\folio\fi}
X
%\def\topglue{\nointerlineskip \vglue-\topskip \vglue}
\topglue 1in % uncomment previous line if your TeX doesn't know this
\centerline{\bf An Introduction to the Z Shell}
\bigskip
\centerline{Paul Falstad}
\centerline{Department of Computer Science} % actually, I'm an undergrad.
\centerline{Princeton University}
\centerline{Princeton, NJ 08544}
\bigskip
{\bf zsh} is a shell designed for interactive use, although it
is also a powerful scripting language. Many of the useful
features of bash, ksh, and tcsh were incorporated into zsh;
many original features were added.
This document details some of the unique features of zsh.
It assumes basic knowledge of the standard UNIX shells;
the intent is to show a reader already familiar with one of the
other major shells what makes zsh more useful or more powerful.
This document is not at all comprehensive; read the manual entry
for a description of the shell that is
complete and concise,
although somewhat overwhelming and devoid of examples.
\beginsection Filename Generation
X
Otherwise known as {\it globbing}, filename generation
is quite extensive in zsh. Of course, it has all the
basics:
\beg
% ls
Makefile file.pro foo.o main.o q.c run234 stuff
bar.o foo link morestuff run123 run240 sub
file.h foo.c main.h pipe run2 run303
% ls *.c
foo.c q.c
% ls *.[co]
bar.o foo.c foo.o main.o q.c
% ls foo.?
foo.c foo.o
% ls *.[^c]
bar.o file.h foo.o main.h main.o
% ls *.[^oh]
foo.c q.c
\end
Also, if the \opt{EXTENDEDGLOB} option is set,
some new features are activated.
For example, the @^@ character negates the pattern following it:
\beg
% setopt extendedglob
% ls -d ^*.c
Makefile file.pro link morestuff run2 run303
bar.o foo main.h pipe run234 stuff
file.h foo.o main.o run123 run240 sub
% ls -d ^*.*
Makefile link pipe run2 run240 stuff
foo morestuff run123 run234 run303 sub
% ls -d ^Makefile
bar.o foo link morestuff run123 run240 sub
file.h foo.c main.h pipe run2 run303
file.pro foo.o main.o q.c run234 stuff
% ls -d *.^c
.rhosts bar.o file.h file.pro foo.o main.h main.o
\end
An expression of the form @<@$x$--$y$@>@ matches a range of integers:
\beg
% ls run<200-300>
run234 run240
% ls run<300-400>
run303
% ls run<-200>
run123 run2
% ls run<300->
run303
% ls run<>
run123 run2 run234 run240 run303
\end
Grouping is possible:
\beg
% ls (foo|bar).*
bar.o foo.c foo.o
% ls *.(c|o|pro)
bar.o file.pro foo.c foo.o main.o q.c
\end
Also, the string @..../@ forces a recursive search of
subdirectories:
\beg
% ls -R
Makefile file.pro foo.o main.o q.c run234 stuff
bar.o foo link morestuff run123 run240 sub
file.h foo.c main.h pipe run2 run303
@space
morestuff:
@space
stuff:
file xxx yyy
@space
stuff/xxx:
foobar
@space
stuff/yyy:
frobar
% ls ..../*bar
stuff/xxx/foobar stuff/yyy/frobar
% ls ..../f*
file.h foo foo.o stuff/xxx/foobar
file.pro foo.c stuff/file stuff/yyy/frobar
% ls *bar*
bar.o
% ls ..../*bar*
bar.o stuff/xxx/foobar stuff/yyy/frobar
% ls stuff/..../*bar*
stuff/xxx/foobar stuff/yyy/frobar
\end
\filbreak
\par
One can add a number of {\it qualifiers} to the end of
any of these patterns, to restrict matches to certain
file types. A qualified pattern is of the form
\begindisplay
{\it pattern}@(@\dot@)@
\enddisplay
with single-letter qualifiers inside the parentheses.
\beg
% alias l='ls -dF'
% l *
Makefile foo* main.h q.c run240
bar.o foo.c main.o run123 run303
file.h foo.o morestuff/ run2 stuff/
file.pro link@@ pipe run234 sub
% l *(/)
morestuff/ stuff/
% l *(@@)
link@@
% l *(*)
foo* link@@ morestuff/ stuff/
% l *(x)
foo* link@@ morestuff/ stuff/
% l *(X)
foo* link@@ morestuff/ stuff/
% l *(R)
bar.o foo* link@@ morestuff/ run123 run240
file.h foo.c main.h pipe run2 run303
file.pro foo.o main.o q.c run234 stuff/
\end
Note that @*(x)@ and @*(*)@ both match executables.
@*(X)@ matches files executable by others, as opposed to
@*(x)@, which matches files executable by the owner.
@*(R)@ and @*(r)@ match readable files;
@*(W)@ and @*(w)@, which checks for writable files.
@*(W)@ is especially important, since it checks for world-writable
files:
\beg
% l *(w)
bar.o foo* link@@ morestuff/ run123 run240
file.h foo.c main.h pipe run2 run303
file.pro foo.o main.o q.c run234 stuff/
% l *(W)
link@@ run240
% l -l link run240
lrwxrwxrwx 1 pfalstad 10 May 23 18:12 link -> /bin/false*
-rw-rw-rw- 1 pfalstad 0 May 23 18:12 run240
\end
You can filter out the symbolic links with the @^@ character:
\beg
% l *(W^@@)
run240
% l *(x)
foo* link@@ morestuff/ stuff/
% l *(x^@@/)
foo*
\end
To find all plain files, you can use @.@:
\beg
% l *(.)
Makefile file.h foo* foo.o main.o run123 run234 run303
bar.o file.pro foo.c main.h q.c run2 run240 sub
% l *(^.)
link@@ morestuff/ pipe stuff/
% l s*(.)
stuff/ sub
% l *(p)
pipe
% l -l *(p)
prw-r--r-- 1 pfalstad 0 May 23 18:12 pipe
\end
@*(U)@ matches all files owned by you.
To search for all files not owned by you, use @*(^U)@:
\beg
% l -l *(^U)
-rw------- 1 subbarao 29 May 23 18:13 sub
\end
This searches for setuid files:
\beg
% l -l *(s)
-rwsr-xr-x 1 pfalstad 16 May 23 18:12 foo*
\end
This checks for a certain user's files:
\beg
% ypmatch subbarao passwd
subbarao:*:3338:35:Kartik Subbarao:/u/subbarao:/usr/princeton/bin/zsh
% l -l *(u3338)
-rw------- 1 subbarao 29 May 23 18:13 sub
\end
\beginsection Startup Files
X
There are five startup files that zsh will read commands from:
\beg
$ZDOTDIR/.zshenv
$ZDOTDIR/.zprofile
$ZDOTDIR/.zshrc
$ZDOTDIR/.zlogin
$ZDOTDIR/.zlogout
\end
If \parm{ZDOTDIR} is not set, then the value of \parm{HOME} is used;
this is the usual case.
\par
@.zshenv@ is sourced on all invocations of the shell,
unless the @-f@ option is set. It should contain commands to set
the command search path, plus other important environment
variables.
@.zshenv@ should not contain commands that produce output
or assume the shell is attached to a tty.
\par
@.zshrc@ is sourced in interactive shells. It should contain
commands to set up aliases, functions, options, key bindings, etc.
Putting commands like @stty@ or ``@echo executing .zshrc....@''
in one's @.zshrc@ is considered bad style.
\par
@.zlogin@ is sourced in login shells. It should contain
commands that should be executed only in login shells.
@.zlogout@ is sourced when login shells exit.
@.zprofile@ is similar to @.zlogin@, except that it is sourced before
@.zshrc@.
@.zprofile@ is meant as an alternative to @.zlogin@ for
ksh fans;
the two are not intended to be used together, although this
could certainly be done if desired.
@.zlogin@ is not the place for alias definitions, options, environment
variable settings, etc.;
as a general rule, it should not change the shell environment
at all. Rather, it should be used to set the terminal type
and run a series of external commands (@fortune@, @msgs@, etc).
\beginsection Shell Functions
X
zsh also allows you to create your own commands by defining shell
functions. For example:
\beg
% yp () {
> ypmatch $1 passwd.byname
> }
% yp pfalstad
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
\end
This function looks up a user in the NIS password map.
The @$1@ expands to the first argument to @yp@.
The function could have been equivalently defined in one of the following
ways:
\beg
% function yp {
> ypmatch $1 passwd.byname
> }
% function yp () {
> ypmatch $1 passwd.byname
> }
\end
Note that aliases are expanded when the function definition is
parsed, not when the function is executed. For example:
\beg
% alias ypmatch=echo
% yp pfalstad
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
\end
Since the alias was defined after the function was parsed, it has
no effect on the function's execution.
However, if we define the function again with the alias in place:
\beg
% function yp () { ypmatch $1 passwd.byname }
% yp pfalstad
pfalstad passwd.byname
\end
it is parsed with the new alias definition in place.
Therefore, in general you must define aliases before functions.
\par
We can make the function take multiple arguments:
\beg
% unalias ypmatch
% yp () {
> for i
> do ypmatch $i passwd.byname
> done
> }
% yp pfalstad subbarao sukthnkr
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
subbarao:*:3338:35:Kartik Subbarao:/u/subbarao:/usr/princeton/bin/zsh
sukthnkr:*:1267:35:Rahul Sukthankar:/u/sukthnkr:/usr/princeton/bin/tcsh
\end
The @for i@ loops through each of the function's arguments,
setting @i@ equal to each of them in turn.
We can also make the function do something sensible
if no arguments are given:
\beg
% yp () {
> if (( $# == 0 ))
> then echo usage: yp name ...; fi
> for i; do ypmatch $i passwd.byname; done
> }
% yp
usage: yp name ...
% yp pfalstad sukthnkr
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
sukthnkr:*:1267:35:Rahul Sukthankar:/u/sukthnkr:/usr/princeton/bin/tcsh
\end
@$#@ is the number of arguments supplied to the function.
If it is equal to zero, we print a usage message; otherwise,
we loop through the arguments, and @ypmatch@ all of them.
\par
Here's a function that selects a random line from a file:
\beg
% randline () {
> integer z=$(wc -l <$1)
> sed -n $[RANDOM % z + 1]p $1
> }
% randline /etc/motd
PHOENIX WILL BE DOWN briefly Friday morning, 5/24/91 from 8 AM to
% randline /etc/motd
SunOS Release 4.1.1 (PHOENIX) #19: Tue May 14 19:03:15 EDT 1991
% randline /etc/motd
| Please use the "msgs" command to read announcements. Refer to the |
% echo $z
X
%
\end
@randline@ has a local variable, @z@, that holds the number of
lines in the file. @$[RANDOM % z + 1]@ expands to a random number
between 1 and @z@. An expression of the form @$[@\dot@]@
expands to the value of the arithmetic expression within the brackets,
and the \parm{RANDOM} variable returns a random number each time it
is referenced. @%@ is the modulus operator, as in C.
Therefore, @sed -n $[RANDOM%z+1]p@ picks a random line from its
input, from 1 to @z@.
\par
Function definitions can be viewed with the @functions@ builtin:
\beg
% functions randline
randline () {
X integer z=$(wc -l <$1)
X sed -n $[RANDOM % z + 1]p $1
X
}
% functions
yp () {
X if let $# == 0
X
X then
X echo usage: yp name ...
X
X fi
X for i
X do
X ypmatch $i passwd.byname
X
X done
X
}
randline () {
X integer z=$(wc -l <$1)
X sed -n $[RANDOM % z + 1]p $1
X
}
\end
Here's another one:
\beg
% cx () { chmod +x $* }
% ls -l foo bar
-rw-r--r-- 1 pfalstad 29 May 24 04:38 bar
-rw-r--r-- 1 pfalstad 29 May 24 04:38 foo
% cx foo bar
% ls -l foo bar
-rwxr-xr-x 1 pfalstad 29 May 24 04:38 bar
-rwxr-xr-x 1 pfalstad 29 May 24 04:38 foo
\end
Note that this could also have been implemented as an alias:
\beg
% chmod 644 foo bar
% alias cx='chmod +x'
% cx foo bar
% ls -l foo bar
-rwxr-xr-x 1 pfalstad 29 May 24 04:38 bar
-rwxr-xr-x 1 pfalstad 29 May 24 04:38 foo
\end
\filbreak\par
Instead of defining a lot of functions in your @.zshrc@,
all of which you may not use,
it is often better to use the @autoload@ builtin.
The idea is, you create a directory where function
definitions are stored, declare the names in
your @.zshrc@, and tell the shell where to look for them.
Whenever you reference a function, the shell
will automatically load it into memory.
\beg
% mkdir /tmp/funs
% cat >/tmp/funs/yp
ypmatch $1 passwd.byname
^D
% cat >/tmp/funs/cx
chmod +x $*
^D
% FPATH=/tmp/funs
% autoload cx yp
% functions cx yp
undefined cx ()
undefined yp ()
% chmod 755 /tmp/funs/{cx,yp}
% yp egsirer
egsirer:*:3214:35:Emin Gun Sirer:/u/egsirer:/bin/sh
% functions yp
yp () {
X ypmatch $1 passwd.byname
}
\end
This idea has other benefits. By adding a @#!@ header
to the files, you can make them double as shell scripts.
(Although it is faster to use them as functions, since a
separate process is not created.)
\beg
% ed /tmp/funs/yp
25
i
#! /usr/local/bin/zsh
.
w
42
q
% </tmp/funs/yp
#! /usr/local/bin/zsh
ypmatch $1 passwd.byname
% /tmp/funs/yp sukthnkr
sukthnkr:*:1267:35:Rahul Sukthankar:/u/sukthnkr:/usr/princeton/bin/tcsh
\end
Now other people, who may not use zsh, or who don't want to
copy all of your @.zshrc@, may use these functions as shell
scripts.
\beginsection Directories
X
One nice feature of zsh is the way it prints directories.
For example, if we set the prompt like this:
\beg
phoenix% PROMPT='%~> '
~> cd src
~/src>
\end
the shell will print the current directory in the prompt,
using the @~@ character.
However, zsh is smarter than most other shells in this respect:
\beg
~/src> cd ~subbarao
~subbarao> cd ~maruchck
~maruchck> cd lib
~maruchck/lib> cd fun
~maruchck/lib/fun> foo=/usr/princeton/common/src
~maruchck/lib/fun> cd ~foo
~foo> cd ..
/usr/princeton/common> cd src
~foo> cd news/nntp
~foo/news/nntp> cd inews
~foo/news/nntp/inews>
\end
Note that zsh prints {\it other} users' directories
in the form @~user@. Also note that you can
set a parameter and use it as a directory name;
zsh will act as if @foo@ is a user
with the login directory @/usr/princeton/common/src@.
This is convenient, especially if you're sick of seeing
prompts like this:
\beg
phoenix:/usr/princeton/common/src/X.V11R4/contrib/clients/xv/docs>
\end
If you get stuck in this position, you can give the current
directory a short name, like this:
\beg
/usr/princeton/common/src/news/nntp/inews> inews=$PWD
/usr/princeton/common/src/news/nntp/inews> echo ~inews
/usr/princeton/common/src/news/nntp/inews
~inews>
\end
When you reference a directory in the form @~inews@,
the shell assumes that you want the directory displayed
in this form; thus simply typing @echo ~inews@ or
@cd ~inews@ causes the prompt to be shortened.
You can define a shell function for this purpose:
\beg
~inews> namedir () { $1=$PWD ; : ~$1 }
~inews> cd /usr/princeton/bin
/usr/princeton/bin> namedir pbin
~pbin> cd /var/spool/mail
/var/spool/mail> namedir spool
~spool> cd .msgs
~spool/.msgs>
\end
You may want to add this one-line function to your
@.zshrc@.
X
zsh can also put the current directory in your title bar,
if you are using a windowing system.
One way to do this is with the @chpwd@ function, which is
automatically executed by the shell whenever you change
directory. If you are using xterm, this will work:
\beg
chpwd () { print -Pn '^[]2;%~^G' }
\end
The @-P@ option tells @print@ to treat its arguments like a prompt
string; otherwise the @%~@ would not be expanded.
The @-n@ option suppresses the terminating newline, as with @echo@.
\par
If you are using an IRIS @wsh@, do this:
\beg
chpwd () { print -Pn '^[P1.y%~^[\' }
\end
The @print -D@ command has other uses. For example, to
print the current directory to standard output in short form,
you can do this:
\beg
% print -D $PWD
~subbarao/src
\end
and to print each component of the path in short form:
\beg
% print -D $path
/bin /usr/bin ~locbin ~locbin/X11 ~/bin
\end
\beginsection Directory Stacks
X
If you use csh, you may know about directory stacks.
The @pushd@ command puts the current directory on the
stack, and changes to a new directory; the @popd@ command
pops a directory off the stack and changes to it.
\beg
phoenix% cd
phoenix% PROMPT='Z %~> '
Z ~> pushd /tmp
/tmp ~
Z /tmp> pushd /usr/etc
/usr/etc /tmp ~
Z /usr/etc> pushd /usr/bin
/usr/bin /usr/etc /tmp ~
Z /usr/bin> popd
/usr/etc /tmp ~
Z /usr/etc> popd
/tmp ~
Z /tmp> pushd /etc
/etc /tmp ~
Z /etc> popd
/tmp ~
\end
zsh's directory stack commands work similarly. One
difference is the way @pushd@ is handled if no arguments
are given. As in csh, this exchanges the top two elements
of the directory stack:
\beg
Z /tmp> dirs
/tmp ~
Z /tmp> pushd
~ /tmp
\end
unless the stack only has one entry:
\beg
Z ~> popd
/tmp
Z /tmp> dirs
/tmp
Z /tmp> pushd
~ /tmp
\end
or unless the \opt{PUSHDTOHOME} option is set:
\beg
Z ~> setopt pushdtohome
Z ~> pushd
~ ~ /tmp
\end
\filbreak\par
As an alternative to using directory stacks in this manner,
we can get something like a {\it directory history}
by setting a few more options and parameters:
\beg
~> DIRSTACKSIZE=8
~> setopt autopushd pushdminus pushdsilent pushdtohome
~> alias dh='dirs -v'
~> cd /tmp
/tmp> cd /usr
/usr> cd bin
/usr/bin> cd ../pub
/usr/pub> dh
0 /usr/pub
1 /usr/bin
2 /usr
3 /tmp
4 ~
/usr/pub> cd -3
/tmp> dh
0 /tmp
1 /usr/pub
2 /usr/bin
3 /usr
4 ~
/tmp> ls =2/df
/usr/bin/df
/tmp> cd -4
~>
\end
Note that @=2@ expanded to the second directory in the
history list, and that @cd -3@ recalled the third
directory in the list.
\par
You may be wondering what all those options do.
\opt{AUTOPUSHD} made @cd@ act like @pushd@.
(@alias cd=pushd@ is not sufficient, for various reasons.)
\opt{PUSHDMINUS} swapped the meaning of @cd +1@ and
@cd -1@; we want them to mean the opposite of what they mean in csh,
because it makes more sense in this scheme, and it's easier to type:
\beg
~> dh
0 ~
1 /tmp
2 /usr/pub
3 /usr/bin
4 /usr
~> unsetopt pushdminus
~> cd +1
/tmp> dh
0 /tmp
1 ~
2 /usr/pub
3 /usr/bin
4 /usr
/tmp> cd +2
/usr/pub>
\end
\goodbreak
\opt{PUSHDSILENT} keeps the shell from printing
the directory stack each time we do a @cd@,
and \opt{PUSHDTOHOME} we mentioned earlier:
\beg
/usr/pub> unsetopt pushdsilent
/usr/pub> cd /etc
/etc /usr/pub /tmp ~ /usr/bin /usr
/etc> cd
~ /etc /usr/pub /tmp ~ /usr/bin /usr
~> unsetopt pushdtohome
~> cd
/etc ~ /usr/pub /tmp ~ /usr/bin /usr
/etc>
\end
\parm{DIRSTACKSIZE} keeps the directory stack
from getting too large, much like \opt{HISTSIZE}:
\beg
/etc> setopt pushdsilent
/etc> cd /
/> cd /
/> cd /
/> cd /
/> cd /
/> cd /
/> cd /
/> cd /
/> dh
0 /
1 /
2 /
3 /
4 /
5 /
6 /
7 /
\end
\beginsection Command/Process Substitution
X
Command substitution in zsh can take two forms.
In the traditional form, a command enclosed in
backquotes (@`@\dot@`@) is replaced on the command line with its output.
This is the form used by the older shells.
Newer shells (like zsh) also provide another form,
@$(@\dot@)@. This form is much easier to nest.
\beg
% ls -l `echo /vmunix`
-rwxr-xr-x 1 root 1209702 May 14 19:04 /vmunix
% ls -l $(echo /vmunix)
-rwxr-xr-x 1 root 1209702 May 14 19:04 /vmunix
% who | grep mad
subbarao ttyt7 May 23 15:02 (mad55sx15.Prince)
pfalstad ttyu1 May 23 16:25 (mad55sx14.Prince)
subbarao ttyu6 May 23 15:04 (mad55sx15.Prince)
pfalstad ttyv3 May 23 16:25 (mad55sx14.Prince)
% who | grep mad | awk '{print $2}'
ttyt7
ttyu1
ttyu6
ttyv3
% cd /dev; ls -l $(who |
> grep $(echo mad) |
> awk '{ print $2 }')
crwx-w---- 1 subbarao 20, 71 May 23 18:35 ttyt7
crw--w---- 1 pfalstad 20, 81 May 23 18:42 ttyu1
crwx-w---- 1 subbarao 20, 86 May 23 18:38 ttyu6
crw--w---- 1 pfalstad 20, 99 May 23 18:41 ttyv3
\end
Many common uses of command substitution, however, are
superseded by other mechanisms of zsh:
\beg
% ls -l `tty`
crw-rw-rw- 1 root 20, 28 May 23 18:35 /dev/ttyqc
% ls -l $TTY
crw-rw-rw- 1 root 20, 28 May 23 18:35 /dev/ttyqc
% ls -l `which rn`
-rwxr-xr-x 1 root 172032 Mar 6 18:40 /usr/princeton/bin/rn
% ls -l =rn
-rwxr-xr-x 1 root 172032 Mar 6 18:40 /usr/princeton/bin/rn
\end
A command name with a @=@ prepended is replaced with its full
pathname. This can be very convenient; constructs like
@`which foo`@ are probably the most common use of
command substitution in a shell.
\par
Another nice feature is process substitution:
\beg
% who | fgrep -f =(print -l root lemke shgchan subbarao)
root console May 19 10:41
lemke ttyq0 May 22 10:05 (narnia:0.0)
lemke ttyr7 May 22 10:05 (narnia:0.0)
lemke ttyrd May 22 10:05 (narnia:0.0)
shgchan ttys1 May 23 16:52 (gaudi.Princeton.)
subbarao ttyt7 May 23 15:02 (mad55sx15.Prince)
subbarao ttyu6 May 23 15:04 (mad55sx15.Prince)
shgchan ttyvb May 23 16:51 (gaudi.Princeton.)
\end
A command of the form @=(@\dot@)@ is replaced with the name of a {\it file}
containing its output. (A command substitution, on the other
hand, is replaced with the output itself.)
@print -l@ is like @echo@, excepts that it prints its arguments
one per line, the way @fgrep@ expects them:
\beg
% print -l foo bar
foo
bar
\end
We could also have written:
\beg
% who | fgrep -f =(echo 'root
> lemke
> shgchan
> subbarao')
\end
Using process substitution,
you can edit the output of a command:
\beg
% ed =(who | fgrep -f ~/.friends)
355
g/lemke/d
w /tmp/filbar
226
q
% cat /tmp/filbar
root console May 19 10:41
shgchan ttys1 May 23 16:52 (gaudi.Princeton.)
subbarao ttyt7 May 23 15:02 (mad55sx15.Prince)
subbarao ttyu6 May 23 15:04 (mad55sx15.Prince)
shgchan ttyvb May 23 16:51 (gaudi.Princeton.)
\end
or easily read archived mail:
\beg
% mail -f =(zcat ~/mail/oldzshmail.Z)
"/tmp/zsha06024": 84 messages, 0 new, 43 unread
> 1 U TO: pfalstad, zsh (10)
X 2 U nytim!tim@@uunet.uu.net, Re: Zsh on Sparc1 /SunOS 4.0.3
X 3 U JAM%TPN@@utrcgw.utc.com, zsh fix (15)
X 4 U djm@@eng.umd.edu, way to find out if running zsh? (25)
X 5 U djm@@eng.umd.edu, Re: way to find out if running zsh? (17)
X 6 r djm@@eng.umd.edu, Meta . (18)
X 7 U jack@@cs.glasgow.ac.uk, Re: problem building zsh (147)
X 8 U nytim!tim@@uunet.uu.net, Re: Zsh on Sparc1 /SunOS 4.0.3
X 9 ursa!jmd, Another fix... (61)
X 10 U pplacewa@@bbn.com, Re: v18i084: Zsh 2.00 - A small complaint (36)
X 11 U lubkin@@cs.rochester.edu, POSIX job control (34)
X 12 U yale!bronson!tan@@uunet.UU.NET
X 13 U brett@@rpi.edu, zsh (36)
X 14 S subbarao, zsh sucks!!!!
X 15 U snibru!d241s008!d241s013!ala@@relay.EU.net, zsh (165)
X 16 U nytim!tim@@uunet.UU.NET, Re: Zsh on Sparc1 /SunOS 4.0.3
X 17 U subbarao, zsh is a junk shell (43)
X 18 U amaranth@@vela.acs.oakland.edu, zsh (33)
43u/84 1: x
% ls -l /tmp/zsha06024
/tmp/zsha06024 not found
\end
Note that the shell creates a temporary file, and deletes it
when the command is finished.
\goodbreak
\beg
% diff =(ls) =(ls -F)
3c3
< fortune
---
> fortune*
10c10
< strfile
---
> strfile*
\end
If you read zsh's man page, you may notice that @<(@\dot@)@
is another form of process substitution which is similar to
@=(@\dot@)@.
There is an important difference between the two.
In the @<(@\dot@)@ case, the shell creates a named pipe (FIFO)
instead of a file. This is better, since it does not
fill up the file system; but it does not work in all cases.
In fact, if we had replaced @=(@\dot@)@ with @<(@\dot@)@ in
the examples above, all of them would have stopped working
except for @fgrep -f <(@\dot@)@.
You can not edit a pipe, or open it as a mail folder;
@fgrep@, however, has no problem with reading
a list of words from a pipe.
You may wonder why @diff <(foo) bar@ doesn't work, since
@foo | diff - bar@ works; this is because @diff@ creates
a temporary file if it notices that one of its arguments
is @-@, and then copies its standard input to the temporary
file.
\beginsection Aliasing
X
Often-used commands can be abbreviated with an alias:
\beg
% alias uc=uncompress
% ls
hanoi.Z
% uc hanoi
% ls
hanoi
\end
or commands with certain desired options:
\beg
% alias fm='finger -m'
% fm root
Login name: root In real life: Operator
Directory: / Shell: /bin/csh
On since May 19 10:41:15 on console 3 days 5 hours Idle Time
No unread mail
No Plan.
X
% alias lock='lock -p -60000'
% lock
lock: /dev/ttyr4 on phoenix. timeout in 60000 minutes
time now is Fri May 24 04:23:18 EDT 1991
Key:
X
% alias l='ls -AF'
% l /
.bash_history kadb*
.bashrc lib@@
.cshrc licensed/
.exrc lost+found/
.login macsyma
@dot
\end
Aliases can also be used to replace old commands:
\beg
% alias grep=egrep ps=sps make=gmake
% alias whoami='echo root'
% whoami
root
\end
or to define new ones:
\beg
% cd /
% alias sz='ls -l | sort -n +3 | tail -10'
% sz
drwxr-sr-x 7 bin 3072 May 23 11:59 etc
drwxrwxrwx 26 root 5120 May 24 04:20 tmp
drwxr-xr-x 2 root 8192 Dec 26 19:34 lost+found
drwxr-sr-x 2 bin 14848 May 23 18:48 dev
-r--r--r-- 1 root 140520 Dec 26 20:08 boot
-rwxr-xr-x 1 root 311172 Dec 26 20:08 kadb
-rwxr-xr-x 1 root 1209695 Apr 16 15:33 vmunix.old
-rwxr-xr-x 1 root 1209702 May 14 19:04 vmunix
-rwxr-xr-x 1 root 1209758 May 21 12:23 vmunix.new.kernelmap.old
-rwxr-xr-x 1 root 1711848 Dec 26 20:08 vmunix.org
% alias rable='ls -AFtrd *(R)' nrable='ls -AFtrd *(^R)'
% rable
README func/ bin/ pub/ News/ src/
nicecolors etc/ scr/ tmp/ iris/ zsh*
% nrable
Mailboxes/ mail/ notes
\end
(The pattern @*(R)@ matches all readable files in the current
directory, and @*(^R)@ matches all unreadable files.)
\par
Most other shells have aliases of this kind ({\it command} aliases).
However, zsh also has {\it global} aliases, which are substituted
anywhere on a line.
Global aliases can be used to abbreviate frequently-typed
usernames, hostnames, etc.
\beg
% alias -g me=pfalstad gun=egsirer mjm=maruchck
% who | grep me
pfalstad ttyp0 May 24 03:39 (mickey.Princeton)
pfalstad ttyp5 May 24 03:42 (mickey.Princeton)
% fm gun
Login name: egsirer In real life: Emin Gun Sirer
Directory: /u/egsirer Shell: /bin/sh
Last login Thu May 23 19:05 on ttyq3 from bow.Princeton.ED
New mail received Fri May 24 02:30:28 1991;
X unread since Fri May 24 02:30:27 1991
% alias -g phx=phoenix.princeton.edu warc=wuarchive.wustl.edu
% ftp warc
Connected to wuarchive.wustl.edu.
\end
\goodbreak
Here are some more interesting uses.
\begindisplay
@% alias -g M='| more' GF='| fgrep -f ~/.friends'@\cr
@% who M #@ {\it pipes the output of @who@ through @more@}\cr
@% who GF #@ {\it see if your friends are on}\cr
@% w GF #@ {\it see what your friends are doing}\cr
\enddisplay
\goodbreak
Another example makes use of zsh's process substitution.
If you miss being able to do this:
\beg
% grep pfalstad /etc/passwd
\end
you can define an alias that will seem more natural
than @ypmatch pfalstad passwd@:
\beg
% alias -g PASS='<(ypcat passwd)'
% grep pfalstad PASS
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
\end
If you're really crazy, you can even call it @/etc/passwd@:
\beg
% alias -g /etc/passwd='<(ypcat passwd)'
% grep pfalstad /etc/passwd
pfalstad:*:3564:35:Paul John Falstad:/u/pfalstad:/usr/princeton/bin/zsh
\end
The last example shows one of the perils of global aliases;
they have a lot of potential to cause confusion.
For example, if you defined a global alias called @|@ (which is
possible), zsh would begin to act very strangely; every pipe
SHAR_EOF
true || echo 'restore of doc/zshintro.tex failed'
fi
echo 'End of part 1'
echo 'File doc/zshintro.tex is continued in part 2'
echo 2 > _shar_seq_.tmp
exit 0
exit 0 # Just in case...
--
Kent Landfield INTERNET: kent@sparky.IMD.Sterling.COM
Sterling Software, IMD UUCP: uunet!sparky!kent
Phone: (402) 291-8300 FAX: (402) 291-4362
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