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% composefs-dump 5 "" composefs "User Commands"
# NAME
composefs-dump - textual file format for composefs content
# DESCRIPTION
Both the *composefs-info* and the *mkcompose* commands support
generation/consumptions of a textual descriptions of the contents of a
composefs image. This can be used to inspect or modify an image, or to
generate an image without having to have a local directory with the
files in it.
The file format is very simple, with one file per line, first with a
11 fixed fields, followed by a variable number of extended attributes
for the file. It is recommended, but not required to include a trailing
newline for the last file.
Fields are separated by a single space, and lines by a single
newline. Extended attributes further use '=' to separate key from
value. Therefore all these characters, as well as non-printable
characters are escaped in the fields ('=' only in xattr fields).
Also, back-slashes have to be escaped as they are used as the
escape mechanism.
Escapes are of the form \xXY which escapes a single byte using two hex
digits. For example \x00 is the zero byte and \xff is the 255 byte.
Optionally, these custom escapes are supported:
**\\\\**
: backslash.
**\\n**
: newline.
**\\r**
: carriage return.
**\\t**
: tab
Optional fields that are not set contain '-', and if a field actually
has that particular value it is escaped.
The fixed fields on a line are (all numbers in base 10 unless
otherwise specified):
**PATH**
: The full, absolute path of the file in the image. Any directories
used as prefix in the path must have been in the file before this
line.
**SIZE**
: The size of the file. This is ignored for directories.
**MODE**
: The st_mode stat field the file in octal, which includes both the
permissions and the file type.
Additionally, if the file is a hardlink, then this field will
start with a single '@' character, and the payload field points
to the target file. Note that all other fields are typically
filled out for a hardlink as the target, but for generation
of a new file we ignore all the fields except the payload.
**NLINK**
: The st_nlink stat field.
**UID**
: The owner uid.
**GID**
: The owner gid.
**RDEV**
: The st_rdev stat field.
**MTIME**
: The modification time in seconds and nanoseconds since the unix
epoch, separated by '.'. Note this is not a float, "1.1" means
one second and one nanosecond.
**PAYLOAD**
: The payload of the file. For symbolic links this means the symlink
targets. For regular files this is the relative pathname for the
backing files. For hardlinks (see **MODE**), this is the path of
another file in this file that this is a hardlink of.
**CONTENT**
: Small files can inline the actual content in the composefs
image. This contains an escaped version of the content.
This must match the size specified in **SIZE**
**DIGEST**
: A fs-verity digest for the file (only used for regular files, and
not if *CONTENT* is set) that will be validated against backing
files when used.
After the fixed fields comes the xattrs, escaped and space-separated in the form
**KEY**=**VALUE**. Note that '=' must be escaped in **KEY**.
# EXAMPLE
```
/ 4096 40755 4 1000 1000 0 1695372970.944925700 - - - security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
/a\x20dir\x20w\x20space 27 40755 2 1000 1000 0 1694598852.869646118 - - - security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
/a-dir 45 40755 2 1000 1000 0 1674041780.601887980 - - - security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
/a-dir/a-file 259 100644 1 1000 1000 0 1695368732.385062094 35/d02f81325122d77ec1d11baba655bc9bf8a891ab26119a41c50fa03ddfb408 - 35d02f81325122d77ec1d11baba655bc9bf8a891ab26119a41c50fa03ddfb408 security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
/a-hardlink 259 @100644 1 1000 1000 0 1695368732.385062094 /a-dir/a-file - 35d02f81325122d77ec1d11baba655bc9bf8a891ab26119a41c50fa03ddfb408 security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
/inline.txt 10 100644 1 1000 1000 0 1697019909.446146440 - some-text\n - security.selinux=unconfined_u:object_r:unlabeled_t:s0\x00
```
# SEE ALSO
**composefs-info(1)**, **mkcomposefs(1)**
[composefs upstream](https://github.com/containers/composefs)
|
