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Set up the shell to be more compatible with the Bourne shell as
standardized by Posix, if possible. This may involve setting
environment variables, or setting options, or similar
implementation-specific actions. This macro is deprecated, since
AS_INIT already invokes it.
Initialize the M4sh environment. This macro calls m4_init, then
outputs the #! /bin/sh line, a notice about where the output was
generated from, and code to sanitize the environment for the rest of the
script. Among other initializations, this sets SHELL to the shell
chosen to run the script (see CONFIG_SHELL), and LC_ALL to
ensure the C locale. Finally, it changes the current diversion to
BODY. AS_INIT is called automatically by AC_INIT
and AT_INIT, so shell code in configure,
config.status, and testsuite all benefit from a sanitized
shell environment.
Emit shell code to start the creation of a subsidiary shell script in
file, including changing file to be executable. This macro
populates the child script with information learned from the parent
(thus, the emitted code is equivalent in effect, but more efficient,
than the code output by AS_INIT, AS_BOURNE_COMPATIBLE, and
AS_SHELL_SANITIZE). If present, comment is output near the
beginning of the child, prior to the shell initialization code, and is
subject to parameter expansion, command substitution, and backslash
quote removal. The
parent script should check the exit status after this macro, in case
file could not be properly created (for example, if the disk was
full). If successfully created, the parent script can then proceed to
append additional M4sh constructs into the child script.
Note that the child script starts life without a log file open, so if
the parent script uses logging (see AS_MESSAGE_LOG_FD), you
must temporarily disable any attempts to use the log file until after
emitting code to open a log within the child. On the other hand, if the
parent script has AS_MESSAGE_FD redirected somewhere besides
‘1’, then the child script already has code that copies stdout to
that descriptor. Currently, the suggested
idiom for writing a M4sh shell script from within another script is:
AS_INIT_GENERATED([file], [[# My child script.
]]) || { AS_ECHO(["Failed to create child script"]); AS_EXIT; }
m4_pushdef([AS_MESSAGE_LOG_FD])dnl
cat >> "file" <<\__EOF__
# Code to initialize AS_MESSAGE_LOG_FD
m4_popdef([AS_MESSAGE_LOG_FD])dnl
# Additional code
__EOF__
This, however, may change in the future as the M4sh interface is stabilized further.
Also, be aware that use of LINENO within the child script may
report line numbers relative to their location in the parent script,
even when using AS_LINENO_PREPARE, if the parent script was
unable to locate a shell with working LINENO support.
Find a shell that supports the special variable LINENO, which
contains the number of the currently executing line. This macro is
automatically invoked by AC_INIT in configure scripts.
Set up variable as_me to be the basename of the currently executing
script. This macro is automatically invoked by AC_INIT in
configure scripts.
Create, as safely as possible, a temporary sub-directory within
dir with a name starting with prefix. prefix should
be 2–4 characters, to make it slightly easier to identify the owner of
the directory. If dir is omitted, then the value of TMPDIR
will be used (defaulting to ‘/tmp’). On success, the name of the
newly created directory is stored in the shell variable tmp. On
error, the script is aborted.
Typically, this macro is coupled with some exit traps to delete the created directory and its contents on exit or interrupt. However, there is a slight window between when the directory is created and when the name is actually known to the shell, so an interrupt at the right moment might leave the temporary directory behind. Hence it is important to use a prefix that makes it easier to determine if a leftover temporary directory from an interrupted script is safe to delete.
The use of the output variable ‘$tmp’ rather than something in the ‘as_’ namespace is historical; it has the unfortunate consequence that reusing this otherwise common name for any other purpose inside your script has the potential to break any cleanup traps designed to remove the temporary directory.
Initialize the shell suitably for configure scripts. This has
the effect of AS_BOURNE_COMPATIBLE, and sets some other
environment variables for predictable results from configuration tests.
For example, it sets LC_ALL to change to the default C locale.
See Special Shell Variables. This macro is deprecated, since
AS_INIT already invokes it.
Next: File Descriptor Macros, Previous: Support for indirect variable names, Up: Programming in M4sh [Contents][Index]