# Comparing remote files

You can compare two files on a remote system and copy changes between the two files.

Before you begin
The Text Compare editor uses the Eclipse text editor to compare two files. You can set preferences for text comparisons using the Compare/Patch preference settings. To open this preference page, click Window > Preferences, then expand the General list item and click Compare/Patch. Using the settings on this page, you can, for example, select the Ignore white space option to control whether or not whitespace changes are shown in the compare viewer. See the related topics for more information on setting text comparison preferences.
When you compare remote files from the Remote Systems view or the z/OS Projects view, the compare editor performs several file checks to ensure that the files you are comparing are fundamentally compatible:

- It checks the record format and record length parameters of the two files and displays a warning if these parameters are different. You have the option of continuing with the comparison or canceling it.
- If you edit either file, it checks the length of each record and, when you save the file, warns you if any record exceeds the maximum record length.
- If you attempt to save a file with records that exceed the maximum record length, it warns you that the records will be truncated and gives you an opportunity to correct the records. The warning message includes detailed information about line numbers that exceed the maximum record length.

About this task
To compare two files on a remote system, do these steps:

1. From the Remote Systems view or the z/OS® Projects view, select two files and then select Compare With > Each Other. The files open side by side in the Text Compare editor. Rational® Developer for System z® locks both files during the Text Compare edit session. If it cannot obtain a lock on either file, it displays a warning message. You can either cancel the compare request or continue with it. If you choose to continue, the file that cannot be locked is opened in read-only mode. If the two files differ either in record format or in record length, a window opens warning you of the difference and prompts you to continue with or cancel the comparison. When the files open, the text compare editor includes line numbers for each file to help you navigate through the files and locate any lines that exceed the maximum length.
2. You can perform the following actions on the files:
   - Click to copy all file changes from left to right.
   - Click to copy all nonconflicting changes from right to left.
   - Click to copy the current change from left to right.
   - Click to copy the current change from right to left.
   - Click to locate the next difference.
   - Click to locate the previous difference.
   - Click to locate the next change.
     Note: Next Change locates a block of text that is different between the files being compared, and Next Difference locates a string within a change block.
   - Click to locate the previous change.
   The compare function uses the Eclipse text editor rather than the System z LPEX Editor, so capabilities that are available when editing remote files using System z LPEX Editor, such as display of virtual record boundaries, are not available.
3. To save your changes, press Ctrl S. If the changes you have made cause any records to exceed the maximum length, Rational Developer for System z displays a File Truncation Warning. You can click the Details button on this warning to see a list of specific line numbers and their length.
4. Click Yes to save your files or No to return to the text compare edit session. If you click No to return to the edit session, the editor positions the file at the first line that exceeds the record length limit.

- z/OS Solutions preferences
  Use the z/OS Solutions preference page to set general preferences for z/OS projects, subprojects, and files.

Parent topic: z/OS Integrated Development Environment (zIDE)
Related tasks
Setting preferences for comparing files
Related reference
Compare/Patch preferences
Compare editor