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cmd_nvedit.c: Add env exists command

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env exists is a way to test (in hush) if an environment variable
exists.  A workaround existed using printenv but this new command
doesn't require all the stdout/stderr redirection to prevent
printing information to the screen.

Example:
$ set testexists 1
$ env exists testexists && echo "yes"
yes
$ env exists testexists || echo "no"
$ set testexists
$ env exists testexists && echo "yes"
$ env exists testexists || echo "no"
no
$

Signed-off-by: Andrew Ruder <andrew.ruder@elecsyscorp.com>
This commit is contained in:
Andrew Ruder 2013-10-22 19:07:34 -05:00 committed by Tom Rini
parent 8948794a27
commit 88733e2c65
2 changed files with 24 additions and 0 deletions
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1
README
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@ -848,6 +848,7 @@ The following options need to be configured:
CONFIG_CMD_ELF * bootelf, bootvx
CONFIG_CMD_ENV_CALLBACK * display details about env callbacks
CONFIG_CMD_ENV_FLAGS * display details about env flags
CONFIG_CMD_ENV_EXISTS * check existence of env variable
CONFIG_CMD_EXPORTENV * export the environment
CONFIG_CMD_EXT2 * ext2 command support
CONFIG_CMD_EXT4 * ext4 command support

23
common/cmd_nvedit.c
View File

@ -1059,6 +1059,23 @@ sep_err:
}
#endif
#if defined(CONFIG_CMD_ENV_EXISTS)
static int do_env_exists(cmd_tbl_t *cmdtp, int flag, int argc,
char * const argv[])
{
ENTRY e, *ep;
if (argc < 2)
return CMD_RET_USAGE;
e.key = argv[1];
e.data = NULL;
hsearch_r(e, FIND, &ep, &env_htab, 0);
return (ep == NULL) ? 1 : 0;
}
#endif
/*
* New command line interface: "env" command with subcommands
*/
@ -1094,6 +1111,9 @@ static cmd_tbl_t cmd_env_sub[] = {
U_BOOT_CMD_MKENT(save, 1, 0, do_env_save, "", ""),
#endif
U_BOOT_CMD_MKENT(set, CONFIG_SYS_MAXARGS, 0, do_env_set, "", ""),
#if defined(CONFIG_CMD_ENV_EXISTS)
U_BOOT_CMD_MKENT(exists, 2, 0, do_env_exists, "", ""),
#endif
};
#if defined(CONFIG_NEEDS_MANUAL_RELOC)
@ -1136,6 +1156,9 @@ static char env_help_text[] =
#if defined(CONFIG_CMD_EDITENV)
"env edit name - edit environment variable\n"
#endif
#if defined(CONFIG_CMD_ENV_EXISTS)
"env exists name - tests for existence of variable\n"
#endif
#if defined(CONFIG_CMD_EXPORTENV)
"env export [-t | -b | -c] [-s size] addr [var ...] - export environment\n"
#endif