Diff for "BashFAQ/090"

Differences between revisions 5 and 7 (spanning 2 versions)

How do I prepend a text to a file (the opposite of >>)?

You cannot do it with bash redirections alone; the opposite of >> does not exist....

To do it in 2 commands with sed: sed "1iTEXTTOPREPEND" filename > tmp mv tmp filename

To insert content at the beginning of a file, you can use an editor:

ex file << EOF
0a
header line 1
header line 2
.
w
EOF

ex will also add a newline character to the end of the file if it's missing.

Or you can rewrite the file, using things like:

{ echo line; cat file ;} >tmpfile && mv tmpfile file
echo line | cat - file > tmpfile && mv tmpfile file

or lots of other solutions.

-  ⇤ ← Revision 5 as of 2009-01-09 14:09:01 → 
  Size: 651
  Editor: 212
  Comment:
+   ← Revision 7 as of 2010-05-26 05:12:24 → ⇥
  Size: 681
  Editor: 99-190-22-125
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 5:
+To do it in 2 commands with sed:
sed "1iTEXTTOPREPEND" filename > tmp
mv tmp filename
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+Line 11:
-ed -s file << EOF
1i
+ex file << EOF
0a
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+Line 19:
-Please note that this will not work if the file is empty. ed will also add a newline character to the end of the file if it's missing.
+ex will also add a newline character to the end of the file if it's missing.