JCL F-UREAD

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Reads and locks a record from an open file into a file buffer.

SYNTAX

F-UREAD file-buffer key
error-cmd-line

F-UR file-buffer key
error-cmd-line

SYNTAX ELEMENTS

file-buffer is the number (1 to 9) of the file buffer with which the file is associated.

key is the key of the record to be read and locked. Can be a literal (not enclosed in quotes), or a direct or indirect reference to a buffer or select register.

error-cmd-line is the line immediately after the F-UREAD command. Only executed if the specified record cannot be read.

NOTES

The F-UREAD command is identical to the F-READ command, except that it also locks the record against access by another process, thus eliminating simultaneous updates.

If you attempt to F-UREAD a record which is already locked, execution will be suspended until the record is unlocked by the other process.

Record locks are released by F-DELETE, F-WRITE or F-FREE commands, or when the program terminates.

It is good practice to F-UREAD a record before you create it. This will reserve the key in the file and avoid double updates. Remember though that the command line immediately following the F-UREAD command will be executed because the record does not exist.

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