Cannot extract tar.gz file - not in gzip format error

Question

I have a dataset file which is in tar.gz format. It is one of 3 dataset files all of which came in as tar.gz. When I run tar -xf filename.tar.gz I get the following error:

gzip: stdin: not in gzip format
tar: Child returned status 1
tar: Error is not recoverable: exiting now

I tried an strace gzip and I get the following output :

execve("/usr/bin/gunzip", ["gunzip", "Malayalam.tar.gz"], 0x7ffdd37de658 /* 50 vars */) = 0
brk(NULL)                               = 0x56362d3ff000
arch_prctl(0x3001 /* ARCH_??? */, 0x7ffea6133010) = -1 EINVAL (Invalid argument)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=73381, ...}) = 0
mmap(NULL, 73381, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7fd8efbe8000
close(3)                                = 0
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360A\2\0\0\0\0\0"..., 832) = 832
pread64(3, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0"..., 784, 64) = 784
pread64(3, "\4\0\0\0\20\0\0\0\5\0\0\0GNU\0\2\0\0\300\4\0\0\0\3\0\0\0\0\0\0\0", 32, 848) = 32
pread64(3, "\4\0\0\0\24\0\0\0\3\0\0\0GNU\0\237\333t\347\262\27\320l\223\27*\202C\370T\177"..., 68, 880) = 68
fstat(3, {st_mode=S_IFREG|0755, st_size=2029560, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7fd8efbe6000
pread64(3, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0"..., 784, 64) = 784
pread64(3, "\4\0\0\0\20\0\0\0\5\0\0\0GNU\0\2\0\0\300\4\0\0\0\3\0\0\0\0\0\0\0", 32, 848) = 32
pread64(3, "\4\0\0\0\24\0\0\0\3\0\0\0GNU\0\237\333t\347\262\27\320l\223\27*\202C\370T\177"..., 68, 880) = 68
mmap(NULL, 2037344, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7fd8ef9f4000
mmap(0x7fd8efa16000, 1540096, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7fd8efa16000
mmap(0x7fd8efb8e000, 319488, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19a000) = 0x7fd8efb8e000
mmap(0x7fd8efbdc000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1e7000) = 0x7fd8efbdc000
mmap(0x7fd8efbe2000, 13920, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7fd8efbe2000
close(3)                                = 0
arch_prctl(ARCH_SET_FS, 0x7fd8efbe7580) = 0
mprotect(0x7fd8efbdc000, 16384, PROT_READ) = 0
mprotect(0x56362ce66000, 8192, PROT_READ) = 0
mprotect(0x7fd8efc27000, 4096, PROT_READ) = 0
munmap(0x7fd8efbe8000, 73381)           = 0
getuid()                                = 1000
getgid()                                = 1000
getpid()                                = 29896
rt_sigaction(SIGCHLD, {sa_handler=0x56362ce5bc30, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7fd8efa370c0}, NULL, 8) = 0
geteuid()                               = 1000
brk(NULL)                               = 0x56362d3ff000
brk(0x56362d420000)                     = 0x56362d420000
getppid()                               = 29893
stat("/home/aswinharidas/Desktop", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
stat(".", {st_mode=S_IFDIR|0755, st_size=4096, ...}) = 0
openat(AT_FDCWD, "/usr/bin/gunzip", O_RDONLY) = 3
fcntl(3, F_DUPFD, 10)                   = 10
close(3)                                = 0
fcntl(10, F_SETFD, FD_CLOEXEC)          = 0
geteuid()                               = 1000
getegid()                               = 1000
rt_sigaction(SIGINT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x56362ce5bc30, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7fd8efa370c0}, NULL, 8) = 0
rt_sigaction(SIGQUIT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGQUIT, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7fd8efa370c0}, NULL, 8) = 0
rt_sigaction(SIGTERM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=SIG_DFL, sa_mask=~[RTMIN RT_1], sa_flags=SA_RESTORER, sa_restorer=0x7fd8efa370c0}, NULL, 8) = 0
read(10, "#!/bin/sh\n# Uncompress files.  T"..., 8192) = 2346
execve("/home/aswinharidas/.local/bin/gzip", ["gzip", "-d", "Malayalam.tar.gz"], 0x56362d3ffc88 /* 50 vars */) = -1 ENOENT (No such file or directory)
execve("/usr/local/sbin/gzip", ["gzip", "-d", "Malayalam.tar.gz"], 0x56362d3ffc88 /* 50 vars */) = -1 ENOENT (No such file or directory)
execve("/usr/local/bin/gzip", ["gzip", "-d", "Malayalam.tar.gz"], 0x56362d3ffc88 /* 50 vars */) = -1 ENOENT (No such file or directory)
execve("/usr/sbin/gzip", ["gzip", "-d", "Malayalam.tar.gz"], 0x56362d3ffc88 /* 50 vars */) = -1 ENOENT (No such file or directory)
execve("/usr/bin/gzip", ["gzip", "-d", "Malayalam.tar.gz"], 0x56362d3ffc88 /* 50 vars */) = 0
brk(NULL)                               = 0x55b64aa7a000
arch_prctl(0x3001 /* ARCH_??? */, 0x7fff34ebc570) = -1 EINVAL (Invalid argument)
access("/etc/ld.so.preload", R_OK)      = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
fstat(3, {st_mode=S_IFREG|0644, st_size=73381, ...}) = 0
mmap(NULL, 73381, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7f70d024a000
close(3)                                = 0
openat(AT_FDCWD, "/lib/x86_64-linux-gnu/libc.so.6", O_RDONLY|O_CLOEXEC) = 3
read(3, "\177ELF\2\1\1\3\0\0\0\0\0\0\0\0\3\0>\0\1\0\0\0\360A\2\0\0\0\0\0"..., 832) = 832
pread64(3, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0"..., 784, 64) = 784
pread64(3, "\4\0\0\0\20\0\0\0\5\0\0\0GNU\0\2\0\0\300\4\0\0\0\3\0\0\0\0\0\0\0", 32, 848) = 32
pread64(3, "\4\0\0\0\24\0\0\0\3\0\0\0GNU\0\237\333t\347\262\27\320l\223\27*\202C\370T\177"..., 68, 880) = 68
fstat(3, {st_mode=S_IFREG|0755, st_size=2029560, ...}) = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f70d0248000
pread64(3, "\6\0\0\0\4\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0@\0\0\0\0\0\0\0"..., 784, 64) = 784
pread64(3, "\4\0\0\0\20\0\0\0\5\0\0\0GNU\0\2\0\0\300\4\0\0\0\3\0\0\0\0\0\0\0", 32, 848) = 32
pread64(3, "\4\0\0\0\24\0\0\0\3\0\0\0GNU\0\237\333t\347\262\27\320l\223\27*\202C\370T\177"..., 68, 880) = 68
mmap(NULL, 2037344, PROT_READ, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) = 0x7f70d0056000
mmap(0x7f70d0078000, 1540096, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x22000) = 0x7f70d0078000
mmap(0x7f70d01f0000, 319488, PROT_READ, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x19a000) = 0x7f70d01f0000
mmap(0x7f70d023e000, 24576, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x1e7000) = 0x7f70d023e000
mmap(0x7f70d0244000, 13920, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x7f70d0244000
close(3)                                = 0
mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f70d0054000
arch_prctl(ARCH_SET_FS, 0x7f70d02495c0) = 0
mprotect(0x7f70d023e000, 16384, PROT_READ) = 0
mprotect(0x55b64a5ef000, 4096, PROT_READ) = 0
mprotect(0x7f70d0289000, 4096, PROT_READ) = 0
munmap(0x7f70d024a000, 73381)           = 0
rt_sigaction(SIGINT, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGHUP, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGPIPE, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGTERM, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXCPU, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGXFSZ, NULL, {sa_handler=SIG_DFL, sa_mask=[], sa_flags=0}, 8) = 0
rt_sigaction(SIGINT, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
rt_sigaction(SIGHUP, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
rt_sigaction(SIGPIPE, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
rt_sigaction(SIGTERM, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
rt_sigaction(SIGXCPU, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
rt_sigaction(SIGXFSZ, {sa_handler=0x55b64a5dd4b0, sa_mask=[HUP INT PIPE TERM XCPU XFSZ], sa_flags=SA_RESTORER, sa_restorer=0x7f70d00990c0}, NULL, 8) = 0
openat(AT_FDCWD, ".", O_RDONLY|O_DIRECTORY) = 3
openat(3, "Malayalam.tar.gz", O_RDONLY|O_NOCTTY|O_NONBLOCK|O_NOFOLLOW) = 4
fstat(4, {st_mode=S_IFREG|0664, st_size=258998272, ...}) = 0
brk(NULL)                               = 0x55b64aa7a000
brk(0x55b64aa9b000)                     = 0x55b64aa9b000
read(4, "\365c\305V\246Ne4\223,\216\215\314 Y%\6M\326\335\n\213o~\270\251\315\251r\231$H"..., 262144) = 262144
write(2, "\ngzip: Malayalam.tar.gz: not in "..., 44
gzip: Malayalam.tar.gz: not in gzip format
) = 44
close(4)                                = 0
exit_group(1)                           = ?
+++ exited with 1 +++

Can anyone help me out find a solution to extract the contents. The file is around 7 GB.

Answer 1

This usually means that though the file is packaged as a gzip file (tar.gz) it has not actually been compressed as a gzip file and might actually be something else.

You should check the metadata of the file to get some hints as to what your file actually is because it's not compressed as a tar.gz file.