输出文件时出现错误：Error in file(file, ifelse(append, "a", "w"))

用R生成外显子和内含子基因注释文件时，经过前面运行，已从Ensembl原始基因注释文件中提取生成consExon和consIntrons的data，最后合并输出为一个文件：

fpath <- head(strsplit(args[1], '/')[[1]], -1) %>% paste(., collapse = '/')
fname <- paste0(tail(strsplit(args[1], '/')[[1]], 1), '_', Sys.Date(), '_constExonsAndIntrons_', args[2], '.gtf')

export(
    object = out[ , -2], # omit gene name
    con = paste(fpath, fname, sep = '/'), append = TRUE
)

结果报错：

Error in file(file, ifelse(append, "a", "w")) : 无法打开链结
此外: Warning message:
In file(file, ifelse(append, "a", "w")) :
无法打开文件'/Homo_sapiens.GRCh38.104.gtf_2021-11-08_constExonsAndIntrons_Ensembl.gtf': 权限不够

求告知解决办法～