SUMMARY

Reads headers from SAC data files into memory.

SYNTAX

READHDR [options] [filelist]

where options is one or more of the following:

MORE
TRUST ON|OFF
COMMIT|ROLLBACK|RECALLTRACE
DIR CURRENT|name

ALL options must preceed any element in the filelist.

INPUT

MORE:
Place the new data file headers in memory AFTER the old ones. If this option is omitted, the new data file headers REPLACE the old ones.

Note:
if the MORE option is not specified, the COMMIT, ROLLBACK, and RECALLTRACE options have no effect.

TRUST ON|OFF:
This option is used to resolve an ambiguity in converting files from SAC to CSS format. When converting the data, matching event IDs could mean the files have identical event information, or they could be an artifact of the merging of these two very different formats. When TRUST is ON, SAC is more likely to accept matching event IDs as identical event information than when TRUST is OFF, depending on the history of READ commands associated with the current data files in memory.

COMMIT:
If the MORE option is specified, the COMMIT option commits headers and waveforms in SAC memory -- removing any previous versions of headers or waveforms from RAM -- prior to reading more files. COMMIT is the default.

ROLLBACK:
If the MORE option is specified, the ROLLBACK option reverts to the last committed version of the header and waveform before reading more files.

RECALLTRACE:
If the MORE option is specified, the RECALLTRACE option:

reverts to the last committed version of the waveform,

reverts to the last committed version of those header variables closely linked to the waveform,

commits those header variables which are loosely linked to the waveform. (use HELP RECALLTRACE for a list of which header variables are committed, and which are rolled back.)

DIR CURRENT:
Read all simple filenames (with or without wildcards) from the current directory. This is the directory from which you started SAC.

DIR name:
Read all simple filenames (with or without wildcards) from the directory called name. This may be a relative or absolute directory name.

filelist:
file | wild .

file:
A legal filename. This may be a simple filename or a pathname. The pathname can be a relative or absolute one. See the DESCRIPTION and EXAMPLES sections of the READ command for more details.

wild:
A wildcard laden token that expands to a list of filenames. See the DESCRIPTION and EXAMPLES sections of the READ command and the WILD command for more details.

MORE:	Place the new data file headers in memory AFTER the old ones. If this option is omitted, the new data file headers REPLACE the old ones.
Note:	if the MORE option is not specified, the COMMIT, ROLLBACK, and RECALLTRACE options have no effect.
TRUST ON\|OFF:	This option is used to resolve an ambiguity in converting files from SAC to CSS format. When converting the data, matching event IDs could mean the files have identical event information, or they could be an artifact of the merging of these two very different formats. When TRUST is ON, SAC is more likely to accept matching event IDs as identical event information than when TRUST is OFF, depending on the history of READ commands associated with the current data files in memory.
COMMIT:	If the MORE option is specified, the COMMIT option commits headers and waveforms in SAC memory -- removing any previous versions of headers or waveforms from RAM -- prior to reading more files. COMMIT is the default.
ROLLBACK:	If the MORE option is specified, the ROLLBACK option reverts to the last committed version of the header and waveform before reading more files.
RECALLTRACE:	If the MORE option is specified, the RECALLTRACE option: reverts to the last committed version of the waveform, reverts to the last committed version of those header variables closely linked to the waveform, commits those header variables which are loosely linked to the waveform. (use HELP RECALLTRACE for a list of which header variables are committed, and which are rolled back.)
DIR CURRENT:	Read all simple filenames (with or without wildcards) from the current directory. This is the directory from which you started SAC.
DIR name:	Read all simple filenames (with or without wildcards) from the directory called name. This may be a relative or absolute directory name.
filelist:	file \| wild .
file:	A legal filename. This may be a simple filename or a pathname. The pathname can be a relative or absolute one. See the DESCRIPTION and EXAMPLES sections of the READ command for more details.
wild:	A wildcard laden token that expands to a list of filenames. See the DESCRIPTION and EXAMPLES sections of the READ command and the WILD command for more details.

DESCRIPTION

This command reads the headers from a set of SAC files into memory. You can then list the header contents (LISTHDR), change header values (CHNHDR), and then write the headers back to disk (WRITEHDR). This is much faster than reading entire files into memory, when only the headers are needed.

All commands which load data into memory have are now monitored to maintain a level of confidence in the event information when moved from the SAC data buffer to the CSS data buffer. For READHDR, when the confidence is HIGH that all the data files are cosistent in the numbering of event IDs, matching event IDs are treated as having identical event information. When the confidence is LOW in READHDR, matching event IDs are understood as an artifact, and new event IDs are generated for the incoming file. For more details use HELP READ.

ERROR MESSAGES

1301: No data files read in.
- haven't given a list of files to read.
- none of the files in the list could be read.
1314: Data file list can't begin with a number.
1315: Maximum number of files in data file list is
1335: Illegal operation---only data file headers in memory.
- only LISTHDR, CHNHDR, and WRITEHDR operations. can be performed after a READHDR.

WARNING MESSAGES

0101: opening file
0108: File does not exist:
0114: reading file
- Normally when SAC encounters one of these errors it skips that file and reads the remainder. These errors can be made to be fatal using the READERR command.

SEE COMMANDS

READ, LISTHDR, CHNHDR, WRITEHDR, READERR, COMMIT, ROLLBACK, RECALLTRACE

LATEST REVISION

Oct. 27, 1998 (Version 0.58)