FILE()

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Read or write text file.

Last reviewed 2026-04-14

FILE(filename[,offset,length,options,format])
Description

Read and write text file in character and line mode.

Examples:

Read mode (byte):

Reads the entire content of the file
same => n,Set(foo=${FILE(/tmp/test.txt)})
Reads from the 11th byte to the end of the file (i.e. skips the first 10)
same => n,Set(foo=${FILE(/tmp/test.txt,10)})
Reads from the 11th to 20th byte in the file (i.e. skip the first 10, then read 10 bytes)
same => n,Set(foo=${FILE(/tmp/test.txt,10,10)})

Read mode (line):

Reads the 3rd line of the file
same => n,Set(foo=${FILE(/tmp/test.txt,3,1,l)})
Reads the 3rd and 4th lines of the file
same => n,Set(foo=${FILE(/tmp/test.txt,3,2,l)})
Reads from the third line to the end of the file
same => n,Set(foo=${FILE(/tmp/test.txt,3,,l)})
Reads the last three lines of the file
same => n,Set(foo=${FILE(/tmp/test.txt,-3,,l)})
Reads the 3rd line of a DOS-formatted file
same => n,Set(foo=${FILE(/tmp/test.txt,3,1,l,d)})

Write mode (byte):

Truncate the file and write bar
same => n,Set(FILE(/tmp/test.txt)=bar)
Append bar
same => n,Set(FILE(/tmp/test.txt,,,a)=bar)
Replace the first byte with bar (replaces 1 character with 3)
same => n,Set(FILE(/tmp/test.txt,0,1)=bar)
Replace 10 bytes beginning at the 21st byte of the file with bar
same => n,Set(FILE(/tmp/test.txt,20,10)=bar)
Replace all bytes from the 21st with bar
same => n,Set(FILE(/tmp/test.txt,20)=bar)
Insert bar after the 4th character
same => n,Set(FILE(/tmp/test.txt,4,0)=bar)

Write mode (line):

Replace the first line of the file with bar
same => n,Set(FILE(/tmp/foo.txt,0,1,l)=bar)
Replace the last line of the file with bar
same => n,Set(FILE(/tmp/foo.txt,-1,,l)=bar)
Append bar to the file with a newline
same => n,Set(FILE(/tmp/foo.txt,,,al)=bar)

Note

If live_dangerously in asterisk.conf is set to no, this function can only be executed from the dialplan, and not directly from external protocols.

Arguments
  • filename required
  • offset - Maybe specified as any number. If negative, offset specifies the number of bytes back from the end of the file.
  • length - If specified, will limit the length of the data read to that size. If negative, trims length bytes from the end of the file.
  • options
    • l - Line mode: offset and length are assumed to be measured in lines, instead of byte offsets.
    • a - In write mode only, the append option is used to append to the end of the file, instead of overwriting the existing file.
    • d - In write mode and line mode only, this option does not automatically append a newline string to the end of a value. This is useful for deleting lines, instead of setting them to blank.
  • format - The format parameter may be used to delimit the type of line terminators in line mode.
    • u - Unix newline format.
    • d - DOS newline format.
    • m - Macintosh newline format.
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Functions
ABS() AES_DECRYPT() AES_ENCRYPT() AGC() AGENT() AMI_CLIENT() ARRAY() AST_CONFIG() AST_SORCERY() BASE64_DECODE() BASE64_ENCODE() BASENAME() BLACKLIST() CALENDAR_BUSY() CALENDAR_EVENT() CALENDAR_QUERY() CALENDAR_QUERY_RESULT() CALENDAR_WRITE() CALLCOMPLETION() CALLERID() CALLERPRES() CDR() CDR_PROP() CHANNEL() CHANNELS() CHANNEL_EXISTS() CHECKSIPDOMAIN() CONFBRIDGE() CONFBRIDGE_CHANNELS() CONFBRIDGE_INFO() CONNECTEDLINE() CSV_QUOTE() CURL() CURLOPT() CUT() DAHDI_CHANNEL() DB() DB_DELETE() DB_EXISTS() DB_KEYCOUNT() DB_KEYS() DEC() DELETE() DENOISE() DEVICE_STATE() DIALGROUP() DIALPLAN_EXISTS() DIGIT_SUM() DIRNAME() DUNDILOOKUP() DUNDIQUERY() DUNDIRESULT() ENUMLOOKUP() ENUMQUERY() ENUMRESULT() ENV() EVAL() EVAL_EXTEN() EVAL_SUB() EXCEPTION() EXISTS() EXPORT() EXTENSION_STATE() FAXOPT() FEATURE() FEATUREMAP() FIELDNUM() FIELDQTY() FILE() FILE_COUNT_LINE() FILE_FORMAT() FILTER() FRAME_DROP() FRAME_TRACE() GEOLOC_PROFILE() GLOBAL() GLOBAL_DELETE() GLOBAL_EXISTS() GROUP() GROUP_COUNT() GROUP_LIST() GROUP_MATCH_COUNT() HANGUPCAUSE() HANGUPCAUSE_KEYS() HASH() HASHKEYS() HINT() HOLD_INTERCEPT() IAXPEER() IAXVAR() ICONV() IF() IFMODULE() IFTIME() IMPORT() INC() ISNULL() JABBER_RECEIVE() JABBER_STATUS() JITTERBUFFER() JSON_DECODE() KEYPADHASH() LEN() LISTFILTER() LOCAL() LOCAL_PEEK() LOCK() LOG_GROUP() LTRIM() MAILBOX_EXISTS() MASTER_CHANNEL() MATH() MAX() MD5() MEETME_INFO() MESSAGE() MESSAGE_DATA() MIN() MINIVMACCOUNT() MINIVMCOUNTER() MIXMONITOR() MUTEAUDIO() ODBC() ODBC_FETCH() PARK_GET_CHANNEL() PASSTHRU() PERIODIC_HOOK() PITCH_SHIFT() PJSIP_AOR() PJSIP_CONTACT() PJSIP_DIAL_CONTACTS() PJSIP_DTMF_MODE() PJSIP_ENDPOINT() PJSIP_HEADER() PJSIP_HEADERS() PJSIP_HEADER_PARAM() PJSIP_INHERITABLE_HEADER() PJSIP_MEDIA_OFFER() PJSIP_MOH_PASSTHROUGH() PJSIP_PARSE_URI() PJSIP_PARSE_URI_FROM() PJSIP_RESPONSE_HEADER() PJSIP_RESPONSE_HEADERS() PJSIP_SEND_SESSION_REFRESH() PJSIP_TRANSFER_HANDLING() POLARITY() POP() PP_EACH_EXTENSION() PP_EACH_USER() PRESENCE_STATE() PUSH() QUEUE_EXISTS() QUEUE_GET_CHANNEL() QUEUE_MEMBER() QUEUE_MEMBER_COUNT() QUEUE_MEMBER_LIST() QUEUE_MEMBER_PENALTY() QUEUE_VARIABLES() QUEUE_WAITING_COUNT() QUOTE() RAND() REALTIME() REALTIME_DESTROY() REALTIME_FIELD() REALTIME_HASH() REALTIME_STORE() RECORDING_INFO() REDIRECTING() REGEX() REPLACE() RTRIM() SAYFILES() SCRAMBLE() SET() SHA1() SHARED() SHELL() SHIFT() SIPPEER() SIP_HEADER() SIP_HEADERS() SMDI_MSG() SMDI_MSG_RETRIEVE() SORT() SPEECH() SPEECH_ENGINE() SPEECH_GRAMMAR() SPEECH_RESULTS_TYPE() SPEECH_SCORE() SPEECH_TEXT() SPRINTF() SQL_ESC() SQL_ESC_BACKSLASHES() SRVQUERY() SRVRESULT() STACK_PEEK() STAT() STIR_SHAKEN() STIR_SHAKEN_ATTESTATION() STRBETWEEN() STRFTIME() STRPTIME() STRREPLACE() SYSINFO() TALK_DETECT() TESTTIME() TIMEOUT() TOLOWER() TONE_DETECT() TOUPPER() TRIM() TRYLOCK() TXTCIDNAME() UNLOCK() UNSHIFT() URIDECODE() URIENCODE() UUID() VALID_EXTEN() VARIABLE_EXISTS() VERSION() VMCOUNT() VM_INFO() VOLUME()
Functions
ABS() AES_DECRYPT() AES_ENCRYPT() AGC() AGENT() AMI_CLIENT() ARRAY() AST_CONFIG() AST_SORCERY() BASE64_DECODE() BASE64_ENCODE() BASENAME() BLACKLIST() CALENDAR_BUSY() CALENDAR_EVENT() CALENDAR_QUERY() CALENDAR_QUERY_RESULT() CALENDAR_WRITE() CALLCOMPLETION() CALLERID() CALLERPRES() CDR() CDR_PROP() CHANNEL() CHANNELS() CHANNEL_EXISTS() CHECKSIPDOMAIN() CONFBRIDGE() CONFBRIDGE_CHANNELS() CONFBRIDGE_INFO() CONNECTEDLINE() CSV_QUOTE() CURL() CURLOPT() CUT() DAHDI_CHANNEL() DB() DB_DELETE() DB_EXISTS() DB_KEYCOUNT() DB_KEYS() DEC() DELETE() DENOISE() DEVICE_STATE() DIALGROUP() DIALPLAN_EXISTS() DIGIT_SUM() DIRNAME() DUNDILOOKUP() DUNDIQUERY() DUNDIRESULT() ENUMLOOKUP() ENUMQUERY() ENUMRESULT() ENV() EVAL() EVAL_EXTEN() EVAL_SUB() EXCEPTION() EXISTS() EXPORT() EXTENSION_STATE() FAXOPT() FEATURE() FEATUREMAP() FIELDNUM() FIELDQTY() FILE() FILE_COUNT_LINE() FILE_FORMAT() FILTER() FRAME_DROP() FRAME_TRACE() GEOLOC_PROFILE() GLOBAL() GLOBAL_DELETE() GLOBAL_EXISTS() GROUP() GROUP_COUNT() GROUP_LIST() GROUP_MATCH_COUNT() HANGUPCAUSE() HANGUPCAUSE_KEYS() HASH() HASHKEYS() HINT() HOLD_INTERCEPT() IAXPEER() IAXVAR() ICONV() IF() IFMODULE() IFTIME() IMPORT() INC() ISNULL() JABBER_RECEIVE() JABBER_STATUS() JITTERBUFFER() JSON_DECODE() KEYPADHASH() LEN() LISTFILTER() LOCAL() LOCAL_PEEK() LOCK() LOG_GROUP() LTRIM() MAILBOX_EXISTS() MASTER_CHANNEL() MATH() MAX() MD5() MEETME_INFO() MESSAGE() MESSAGE_DATA() MIN() MINIVMACCOUNT() MINIVMCOUNTER() MIXMONITOR() MUTEAUDIO() ODBC() ODBC_FETCH() PARK_GET_CHANNEL() PASSTHRU() PERIODIC_HOOK() PITCH_SHIFT() PJSIP_AOR() PJSIP_CONTACT() PJSIP_DIAL_CONTACTS() PJSIP_DTMF_MODE() PJSIP_ENDPOINT() PJSIP_HEADER() PJSIP_HEADERS() PJSIP_HEADER_PARAM() PJSIP_INHERITABLE_HEADER() PJSIP_MEDIA_OFFER() PJSIP_MOH_PASSTHROUGH() PJSIP_PARSE_URI() PJSIP_PARSE_URI_FROM() PJSIP_RESPONSE_HEADER() PJSIP_RESPONSE_HEADERS() PJSIP_SEND_SESSION_REFRESH() PJSIP_TRANSFER_HANDLING() POLARITY() POP() PP_EACH_EXTENSION() PP_EACH_USER() PRESENCE_STATE() PUSH() QUEUE_EXISTS() QUEUE_GET_CHANNEL() QUEUE_MEMBER() QUEUE_MEMBER_COUNT() QUEUE_MEMBER_LIST() QUEUE_MEMBER_PENALTY() QUEUE_VARIABLES() QUEUE_WAITING_COUNT() QUOTE() RAND() REALTIME() REALTIME_DESTROY() REALTIME_FIELD() REALTIME_HASH() REALTIME_STORE() RECORDING_INFO() REDIRECTING() REGEX() REPLACE() RTRIM() SAYFILES() SCRAMBLE() SET() SHA1() SHARED() SHELL() SHIFT() SIPPEER() SIP_HEADER() SIP_HEADERS() SMDI_MSG() SMDI_MSG_RETRIEVE() SORT() SPEECH() SPEECH_ENGINE() SPEECH_GRAMMAR() SPEECH_RESULTS_TYPE() SPEECH_SCORE() SPEECH_TEXT() SPRINTF() SQL_ESC() SQL_ESC_BACKSLASHES() SRVQUERY() SRVRESULT() STACK_PEEK() STAT() STIR_SHAKEN() STIR_SHAKEN_ATTESTATION() STRBETWEEN() STRFTIME() STRPTIME() STRREPLACE() SYSINFO() TALK_DETECT() TESTTIME() TIMEOUT() TOLOWER() TONE_DETECT() TOUPPER() TRIM() TRYLOCK() TXTCIDNAME() UNLOCK() UNSHIFT() URIDECODE() URIENCODE() UUID() VALID_EXTEN() VARIABLE_EXISTS() VERSION() VMCOUNT() VM_INFO() VOLUME()