HP-UX Reference (11i v2 03/08) - 1 User Commands A-M (vol 1)

k
ksh(1) ksh(1)
0 is set to the function name. When the function completes or issues a
return, ksh restores the posi-
tional parameter list and executes any trap set on
EXIT within the function. The value of a function is
the value of the last command executed. A function is executed in the current shell process. If a com-
mand name is not a special command or a user-defined function,
ksh creates a process and attempts
to execute the command using
exec (see exec(2)).
The shell parameter
PATH defines the search path for the directory containing the command. Alterna-
tive directory names are separated by a colon (
:). The default path is /usr/bin: (specifying
/usr/bin and the current directory in that order). Note that the current directory is specified by a null
path name which can appear immediately after the equals sign, between colon delimiters, or at the end of
the path list. The search path is not used if the command name contains a
/. Otherwise, each directory
in the path is searched for an executable file. If the file has execute permissions but is not a directory or
an executable object code file, it is assumed to be a script file, which is a file of data for an interpreter. If
the first two characters of the script file are
#!, exec (see exec(2)) expects an interpreter path name to
follow.
exec then attempts to execute the specified interpreter as a separate process to read the entire
script file. If a call to exec
fails, /usr/bin/ksh is spawned to interpret the script file. All non-
exported aliases, functions, and named parameters are removed in this case. If the shell command file
does not have read permission, or if the setuid and/or setgid bits are set on the file, the shell executes an
agent to set up the permissions and execute the shell with the shell command file passed down as an open
file. A parenthesized command is also executed in a sub-shell without removing non-exported quantities.
Command Re-entry
The text of the last
HISTSIZE (default 128) commands entered from a terminal device is saved in a his-
tory file. The file
$HOME/.sh_history
is used if the HISTFILE variable is not set or writable. A
shell can access the commands of all interactive shells that use the same named
HISTFILE. The spe-
cial command fc is used to list or edit a portion of this file. The portion of the file to be edited or listed
can be selected by number or by giving the first character or characters of the command. A single com-
mand or range of commands can be specified. If no editor program is specified as an argument to
fc, the
value of the
FCEDIT parameter is used. If FCEDIT is not defined, /usr/bin/ed is used. The edited
command is printed and re-executed upon leaving the editor. The editor name - is used to skip the edit-
ing phase and to re-execute the command. In this case a substitution parameter of the form old
=new can
be used to modify the command before execution. For example, if
r is aliased to
fc -e -, typing r
bad=good c re-executes the most recent command that starts with the letter c and replaces the first
occurrence of the string bad with the string good.
The history file will be trimmed when all of the following conditions occurs:
Its size is greater than four kilobytes.
The number of commands in it is more than HISTSIZE.
The file has not been modified in the last ten minutes.
The user has write permission for the directory in which the history file resides.
If any one of the above conditions does not occur, the history file will not be trimmed. When the history
file is trimmed, the latest
HISTSIZE commands will be available in the history file.
Special Commands
The following simple-commands are executed in the shell process. They permit input/output redirection.
Unless otherwise indicated, file descriptor 1 is the default output location and the exit status, when there
are no syntax errors, is zero. Commands that are preceded by % or %% are treated specially in the fol-
lowing ways:
1. Variable assignment lists preceding the command remain in effect when the command com-
pletes.
2. I/O redirections are processed after variable assignments.
3. Certain errors cause a script that contains them to abort.
4. Words following a command preceded by %% that are in the format of a variable assignment
are expanded with the same rules as a variable assignment. This means that tilde substitution
is performed after the = sign and word splitting and file name generation are not performed.
%:[ arg ... ] The command only expands parameters. A zero exit code is returned.
%.file [ arg ... ]
Read and execute commands from file and return. The commands are executed in the
current shell environment. The search path specified by PATH is used to find the
HP-UX 11i Version 2: August 2003 − 11 − Hewlett-Packard Company Section 1−−413